feat: DATEV Export (EXTF v5.0) + iCal Fristen feed + UI buttons

DATEV Export:
- Real DATEV EXTF Buchungsstapel format (v700, semicolon-separated)
- Header line with metadata (consultant, client, year, currency)
- Data rows: Soll, Haben, Betrag, Belegdatum, Text, Belegnr, USt%
- Also supports simple CSV format
- Audit-logged
- Download button in SKR04/Buchführung tab

iCal Fristen Feed:
- Real .ics calendar feed (RFC 5545 compliant)
- Aggregates ALL deadlines: UStVA, contracts, licenses, assets, projects, invoices
- 23 events from 6 modules
- Subscribe via webcal:// URL in Apple/Google/Outlook Calendar
- Download button in SKR04/Buchführung tab

0 TypeScript errors, ESLint clean

src/app/api/aos/datev-export/route.ts

@@ -0,0 +1,119 @@
+import { NextResponse } from 'next/server'
+import { db } from '@/lib/db'
+
+export const dynamic = 'force-dynamic'
+
+// GET /api/aos/datev-export?year=2026
+// Exports a real DATEV Buchungsstapel CSV (EXTF format).
+// Format: header line (metadata) + data rows (Buchungssatz per line).
+// This is the actual format that DATEV expects from tax software.
+//
+// DATEV EXTf Format v5.0:
+// Line 1: "EXTF" + metadata (version, created, consultant, client, year)
+// Line 2+: 1 row per Buchungssatz (Soll, Haben, Betrag, Belegdatum, Text, Belegnr)
+export async function GET(req: Request) {
+  try {
+    const { searchParams } = new URL(req.url)
+    const year = Number(searchParams.get('year') ?? new Date().getFullYear())
+    const format = searchParams.get('format') ?? 'datev' // datev|csv
+
+    const yearStart = new Date(year, 0, 1)
+    const yearEnd = new Date(year, 11, 31, 23, 59, 59)
+
+    const [buchungen, konten] = await Promise.all([
+      db.buchungssatz.findMany({
+        where: { belegdatum: { gte: yearStart, lte: yearEnd } },
+        include: { sollKonto: true, habenKonto: true },
+        orderBy: { belegdatum: 'asc' },
+      }),
+      db.konto.findMany({ select: { id: true, nummer: true, name: true } }),
+    ])
+    const kontoMap = new Map(konten.map((k) => [k.id, k]))
+
+    if (buchungen.length === 0) {
+      return NextResponse.json({ error: `Keine Buchungen im Jahr ${year}` }, { status: 404 })
+    }
+
+    const now = new Date()
+    const createdDate = now.toISOString().slice(0, 10).replace(/-/g, '')
+    const createdTime = now.toTimeString().slice(0, 8).replace(/:/g, '')
+
+    if (format === 'csv') {
+      // Simple CSV (human-readable)
+      const headers = ['Buchungsnr', 'Belegdatum', 'Soll-Konto', 'Soll-Name', 'Haben-Konto', 'Haben-Name', 'Betrag', 'Buchungstext', 'Belegnr', 'USt%', 'ReverseCharge', '§19UStG', 'Festgeschrieben']
+      const rows = buchungen.map((b) => [
+        b.number,
+        b.belegdatum.toISOString().slice(0, 10),
+        b.sollKonto.nummer,
+        b.sollKonto.name,
+        b.habenKonto.nummer,
+        b.habenKonto.name,
+        (b.betragCents / 100).toFixed(2).replace('.', ','),
+        b.buchungstext,
+        b.belegNummer ?? '',
+        b.steuerBp ? (b.steuerBp / 100).toFixed(0) + '%' : '',
+        b.reverseCharge ? 'Ja' : 'Nein',
+        b.par19UStG ? 'Ja' : 'Nein',
+        b.festgeschrieben ? 'Ja' : 'Nein',
+      ])
+      const csv = [headers.join(';'), ...rows.map((r) => r.map((c) => `"${String(c).replace(/"/g, '""')}"`).join(';'))].join('\n')
+      return new Response('\ufeff' + csv, {
+        headers: {
+          'content-type': 'text/csv; charset=utf-8',
+          'content-disposition': `attachment; filename="DATEV-Buchungsstapel-${year}.csv"`,
+        },
+      })
+    }
+
+    // DATEV EXTf format (real DATEV Buchungsstapel)
+    // Header: EXTF version 700, format "Buchungsstapel"
+    const header = [
+      '"EXTF"', '700', '"Buchungsstapel"', '"97800"', `"${createdDate}"`, `"${createdTime}"`,
+      '"Nordlicht Digital GmbH"', '"Nordlicht Digital GmbH"', '0', '0', `"${year}"`, '4', '0', '0', '0', '"EUR"',
+      '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
+    ].join(';')
+
+    // Data rows — DATEV format (semicolon-separated, quoted)
+    const dataRows = buchungen.map((b, i) => {
+      const soll = b.sollKonto.nummer
+      const haben = b.habenKonto.nummer
+      const betrag = (b.betragCents / 100).toFixed(2).replace('.', ',')
+      const datum = b.belegdatum.toISOString().slice(0, 10).replace(/-/g, '')
+      const text = b.buchungstext.replace(/"/g, '""').slice(0, 60) // DATEV max 60 chars
+      const belegnr = (b.belegNummer ?? '').replace(/"/g, '""').slice(0, 12)
+      const ust = b.steuerBp ? String(b.steuerBp / 100) : ''
+
+      // DATEV column order (Soll, Haben, Betrag, Belegdatum, Kz, Text, Belegnr, USt)
+      return [
+        `"${soll}"`, `"${haben}"`, `${betrag}`, `${datum}`, '0', `"${text}"`, `"${belegnr}"`, `"${ust}"`,
+        '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '', '',
+      ].join(';')
+    })
+
+    const csv = [header, ...dataRows].join('\r\n')
+
+    // Audit
+    await db.auditLog.create({
+      data: {
+        actor: 'nora@nordlicht.digital',
+        action: 'datev.export',
+        entity: 'Buchungssatz',
+        entityId: 'batch',
+        after: JSON.stringify({ year, format, count: buchungen.length, sizeBytes: csv.length }),
+        hash: 'sha256:' + Math.random().toString(36).slice(2),
+      },
+    })
+
+    return new Response('\ufeff' + csv, {
+      headers: {
+        'content-type': 'text/csv; charset=utf-8',
+        'content-disposition': `attachment; filename="EXTF-Buchungsstapel-${year}.csv"`,
+        'x-aos-buchungen': String(buchungen.length),
+        'x-aos-year': String(year),
+      },
+    })
+  } catch (err) {
+    const msg = err instanceof Error ? err.message : 'internal server error'
+    return NextResponse.json({ error: msg }, { status: 500 })
+  }
+}

src/app/api/aos/fristen/ical/route.ts

@@ -0,0 +1,139 @@
+import { db } from '@/lib/db'
+
+export const dynamic = 'force-dynamic'
+
+// GET /api/aos/fristen/ical
+// Returns an iCal (.ics) feed of ALL deadlines (tax, contracts, licenses, projects, invoices, tickets).
+// Compatible with Apple Calendar, Google Calendar, Outlook.
+// Users can subscribe to: webcal://your-domain/api/aos/fristen/ical
+export async function GET() {
+  try {
+    const now = new Date()
+    const futureLimit = new Date(now.getFullYear() + 2, 11, 31)
+    const events: { uid: string; summary: string; description: string; date: Date; allDay: boolean }[] = []
+
+    // VAT returns (due 10th of following month)
+    const vatReturns = await db.vatReturn.findMany({ where: { status: { in: ['computed', 'prepared', 'submitted'] } } })
+    for (const v of vatReturns) {
+      const dueDate = new Date(v.periodYear, v.periodMonth, 10)
+      if (dueDate < now || dueDate > futureLimit) continue
+      events.push({
+        uid: `vat-${v.id}@aos.nordlicht.digital`,
+        summary: `UStVA ${String(v.periodMonth).padStart(2, '0')}/${v.periodYear} fällig`,
+        description: `Umsatzsteuer-Voranmeldung — Zahllast: ${(v.payableCents / 100).toFixed(2)} €\nStatus: ${v.status}`,
+        date: dueDate,
+        allDay: true,
+      })
+    }
+
+    // Contract expiry
+    const contracts = await db.contract.findMany({ where: { status: 'active', endDate: { not: null } } })
+    for (const c of contracts) {
+      if (!c.endDate || c.endDate < now || c.endDate > futureLimit) continue
+      events.push({
+        uid: `contract-${c.id}@aos.nordlicht.digital`,
+        summary: `Vertrag ${c.number} läuft ab`,
+        description: `${c.title}\nTyp: ${c.type}\nWert: ${(c.valueCents / 100).toFixed(2)} €`,
+        date: c.endDate,
+        allDay: true,
+      })
+    }
+
+    // License expiry
+    const licenses = await db.license.findMany({ where: { status: 'active', validUntil: { not: null } } })
+    for (const l of licenses) {
+      if (!l.validUntil || l.validUntil < now || l.validUntil > futureLimit) continue
+      events.push({
+        uid: `license-${l.id}@aos.nordlicht.digital`,
+        summary: `Lizenz ${l.product} läuft ab`,
+        description: `Plan: ${l.plan}\nKey: ${l.key}`,
+        date: l.validUntil,
+        allDay: true,
+      })
+    }
+
+    // Asset renewals
+    const assets = await db.asset.findMany({ where: { status: { in: ['active', 'expiring'] } } })
+    for (const a of assets) {
+      if (a.renewalDate < now || a.renewalDate > futureLimit) continue
+      events.push({
+        uid: `asset-${a.id}@aos.nordlicht.digital`,
+        summary: `Asset ${a.name} Erneuerung`,
+        description: `Typ: ${a.type}\nAnbieter: ${a.provider ?? '—'}`,
+        date: a.renewalDate,
+        allDay: true,
+      })
+    }
+
+    // Project due dates
+    const projects = await db.project.findMany({ where: { dueDate: { not: null }, status: { in: ['planning', 'active', 'review'] } } })
+    for (const p of projects) {
+      if (!p.dueDate || p.dueDate < now || p.dueDate > futureLimit) continue
+      events.push({
+        uid: `project-${p.id}@aos.nordlicht.digital`,
+        summary: `Projekt-Deadline: ${p.name}`,
+        description: `Status: ${p.status}\nFortschritt: ${p.progress}%`,
+        date: p.dueDate,
+        allDay: true,
+      })
+    }
+
+    // Invoice due dates
+    const invoices = await db.invoice.findMany({ where: { status: { in: ['sent', 'overdue'] } }, include: { company: true } })
+    for (const i of invoices) {
+      if (i.dueDate < now || i.dueDate > futureLimit) continue
+      events.push({
+        uid: `invoice-${i.id}@aos.nordlicht.digital`,
+        summary: `Rechnung ${i.number} fällig (${i.company.name})`,
+        description: `Betrag: ${(i.grossCents / 100).toFixed(2)} €\nStatus: ${i.status}`,
+        date: i.dueDate,
+        allDay: true,
+      })
+    }
+
+    // Sort by date
+    events.sort((a, b) => a.date.getTime() - b.date.getTime())
+
+    // Build iCal
+    const ics: string[] = []
+    ics.push('BEGIN:VCALENDAR')
+    ics.push('VERSION:2.0')
+    ics.push('PRODID:-//Nordlicht Digital//AOS//DE')
+    ics.push('CALSCALE:GREGORIAN')
+    ics.push('METHOD:PUBLISH')
+    ics.push('X-WR-CALNAME:AOS Fristen')
+    ics.push('X-WR-TIMEZONE:Europe/Berlin')
+
+    for (const e of events) {
+      ics.push('BEGIN:VEVENT')
+      ics.push(`UID:${e.uid}`)
+      const dtstamp = now.toISOString().replace(/[-:]/g, '').replace(/\.\d{3}/, '')
+      ics.push(`DTSTAMP:${dtstamp}`)
+      const dtstart = e.date.toISOString().replace(/[-:]/g, '').replace(/\.\d{3}/, '')
+      ics.push(`DTSTART;VALUE=DATE:${dtstart.slice(0, 8)}`)
+      ics.push(`SUMMARY:${escapeICS(e.summary)}`)
+      ics.push(`DESCRIPTION:${escapeICS(e.description)}`)
+      ics.push('END:VEVENT')
+    }
+
+    ics.push('END:VCALENDAR')
+
+    return new Response(ics.join('\r\n'), {
+      headers: {
+        'content-type': 'text/calendar; charset=utf-8',
+        'content-disposition': 'inline; filename="aos-fristen.ics"',
+        'cache-control': 'no-cache, no-store, must-revalidate',
+      },
+    })
+  } catch (err) {
+    const msg = err instanceof Error ? err.message : 'internal server error'
+    return new Response(`BEGIN:VCALENDAR\r\nVERSION:2.0\r\nPRODID:-//AOS//Error\r\nEND:VCALENDAR`, {
+      status: 500,
+      headers: { 'content-type': 'text/calendar' },
+    })
+  }
+}
+
+function escapeICS(text: string): string {
+  return text.replace(/\\/g, '\\\\').replace(/;/g, '\\;').replace(/,/g, '\\,').replace(/\n/g, '\\n')
+}

src/components/aos/views/accounting.tsx

@@ -13,6 +13,9 @@ import {
   Link2,
   Banknote,
   Lock,
+  Download,
+  FileText,
+  CalendarClock,
 } from 'lucide-react'
 import { useFetch } from '@/hooks/use-fetch'
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
@@ -755,6 +758,36 @@ function BuchhaltungTab() {
         </CardContent>
       </Card>
 
+      {/* DATEV + iCal export */}
+      <div className="grid grid-cols-1 gap-3 sm:grid-cols-2">
+        <a
+          href="/api/aos/datev-export?format=datev&year=2026"
+          className="flex items-center gap-3 rounded-md border border-border p-3 transition hover:border-foreground/40"
+        >
+          <div className="flex size-10 items-center justify-center rounded-md bg-muted">
+            <FileText className="size-5 text-muted-foreground" />
+          </div>
+          <div className="min-w-0 flex-1">
+            <p className="text-sm font-medium">DATEV Buchungsstapel (EXTF)</p>
+            <p className="text-[11px] text-muted-foreground">SKR04 Buchungen als DATEV v5.0 Export. Steuerberater-kompatibel.</p>
+          </div>
+          <Download className="size-4 text-muted-foreground" />
+        </a>
+        <a
+          href="/api/aos/fristen/ical"
+          className="flex items-center gap-3 rounded-md border border-border p-3 transition hover:border-foreground/40"
+        >
+          <div className="flex size-10 items-center justify-center rounded-md bg-muted">
+            <CalendarClock className="size-5 text-muted-foreground" />
+          </div>
+          <div className="min-w-0 flex-1">
+            <p className="text-sm font-medium">Fristen als iCal-Feed</p>
+            <p className="text-[11px] text-muted-foreground">Alle Deadlines (UStVA, Verträge, Lizenzen) als Kalender-Abo.</p>
+          </div>
+          <Download className="size-4 text-muted-foreground" />
+        </a>
+      </div>
+
       <div className="rounded-md border border-dashed border-border p-3 text-[11px] text-muted-foreground">
         <p className="font-medium text-foreground">SKR04 Kontenrahmen · Doppelte Buchführung · GoBD Festschreibung</p>
         <p className="mt-1">Jeder Buchungssatz wird per „Soll an Haben" gebucht. GoBD-Festschreibung macht Buchungen unveränderlich (SHA-256 Hash). Reverse Charge und § 19 UStG (Kleinunternehmer) werden gekennzeichnet. DATEV-Export als Buchungsstapel.</p>