feat: Haben-clone + client portal privacy fix

Client Portal privacy (şirket sırrı):
- Removed PRD references from client-facing text
- Removed 'Projekt-isolierter Zugriff' technical term
- Changed to 'Sichere Verbindung' / 'Sicher geschützt'
- Onboarding overlay only shows to agency users (not portal)

Haben-cloned features (Almanya/EU muhasebe uyumu):
- Belege: content-addressed receipts (SHA-256 hash, GoBD retention 8/6 years)
- Pauschalen: Homeoffice (€6.92/day), Kilometer (€0.30/km), Verpflegung (€14/€24/€28)
  - EStG § 4 Abs. 5, § 9 Abs. 1 compliant rates (2026)
- Anlagen & AfA: Anlagenverzeichnis with linear depreciation
  - GWG (≤€800 Sofortabschreibung, § 6 Abs. 2 EStG)
  - Sammelposten (€251-€1000, § 6 Abs. 2a EStG, 5 years)
  - Annual AfA computation + accumulated AfA + book value
- Kassenbuch: cash book (§ 146 AO, § 22 UStG)
  - Immutable (GoBD), running balance, audit-logged
  - Gapless numbering (KAS-2026-XXXX)

Seed data: 5 Belege, 7 Pauschalen, 5 Anlagen, 5 Kassenbuch entries
TypeScript: 0 errors | ESLint: clean

prisma/schema.prisma

@@ -568,6 +568,106 @@ model Article {
   updatedAt   DateTime @updatedAt
 }
 
+// ---------------------------------------------------------------------------
+// Haben-cloned features: Belege, Pauschalen, Anlagen/AfA, Kasse
+// ---------------------------------------------------------------------------
 
+// Belege (receipts/documents) — content-addressed storage (PRD §5.5)
+model Beleg {
+  id            String   @id @default(cuid())
+  number        String   @unique // gapless, e.g. BEL-2026-0001
+  type          String   // rechnung-eingang|rechnung-ausgang|quittung|kassenbeleg|bankbeleg|sonstiges
+  // content-addressed (SHA-256 hash of the file content)
+  fileHash      String   @unique
+  fileName      String
+  fileType      String   // application/pdf, image/jpeg, etc.
+  fileSizeBytes Int
+  // metadata extracted from the document
+  vendor        String?  // Rechnungssteller
+  invoiceNumber String?  // Rechnungsnummer des Lieferanten
+  amountCents   Int?     // Bruttobetrag auf dem Beleg
+  amountNetCents Int?    // Netto (falls extrahiert)
+  taxBp         Int?     // USt %
+  bookingDate   DateTime?
+  // linking
+  expenseId     String?  // link to Expense if billable
+  invoiceId     String?  // link to Invoice if outgoing
+  // OCR / AI
+  ocrText       String?  // extracted text (optional, via Jina/AI)
+  // GoBD
+  archivedAt    DateTime?
+  retentionUntil DateTime? // Aufbewahrung bis
+  createdAt     DateTime @default(now())
+}
 
+// Pauschalen (flat-rate allowances) — Homeoffice, Kilometer, Verpflegung
+model Pauschale {
+  id            String   @id @default(cuid())
+  type          String   // homeoffice|kilometer|verpflegung
+  // homeoffice: €4.17/day (2026: €6.92/day up to €1.260/year)
+  // kilometer: €0.30/km (car), €0.38/km (car w/ pass), or actual
+  // verpflegung: €14 (8-14h), €24 (>14h, same day), €28 (overnight)
+  date          DateTime
+  userId        String?  // employee
+  amountCents   Int      // computed amount
+  // details per type
+  days          Int?     // homeoffice: 1; verpflegung: 1
+  km            Int?     // kilometer: distance
+  vehicleType   String?  // kilometer: auto|rad|fuss
+  tripPurpose   String?  // kilometer: geschäftlich|fortbildung|umzug
+  hoursAway     Int?     // verpflegung: hours away from office
+  overnight     Boolean  @default(false) // verpflegung: overnight stay
+  description   String?
+  projectId     String?  // link to project if billable
+  expenseId     String?  // link to generated expense
+  createdAt     DateTime @default(now())
+}
+
+// Anlagenverzeichnis & AfA (asset register + depreciation)
+model Anlage {
+  id              String   @id @default(cuid())
+  number          String   @unique // e.g. ANL-2026-0001
+  name            String   // "MacBook Pro 16"
+  category        String   // hardware|software|mobiliar|fahrzeug|immobilie
+  // acquisition
+  purchaseDate    DateTime
+  purchaseCostCents Int    // Anschaffungskosten (netto)
+  taxBp           Int      @default(1900) // USt bei Anschaffung
+  // AfA (depreciation)
+  afaMethod       String   @default("linear") // linear|degressiv
+  usefulLifeYears Int      @default(3) // Nutzungsdauer (AfA-Tabelle)
+  salvageValueCents Int    @default(0) // Restwert
+  // GWG (Geringwertiger Wirtschaftsgüter ≤ €800 net → Sofortabschreibung)
+  isGWG           Boolean  @default(false) // GWG ≤ €800 → immediate expense
+  // Sammelposten (€251-€1000 → Sammelabschreibung über 5 Jahre)
+  isSammelposten  Boolean  @default(false)
+  // computed
+  annualAfaCents  Int      @default(0) // jährliche AfA
+  accumulatedAfaCents Int  @default(0) // kumulierte AfA
+  bookValueCents  Int      @default(0) // Buchwert (purchase - accumulated AfA)
+  // status
+  status          String   @default("active") // active|sold|scrapped|fully-depreciated
+  soldDate        DateTime?
+  soldPriceCents  Int?
+  createdAt       DateTime @default(now())
+  updatedAt       DateTime @updatedAt
+}
+
+// Kassenbuch (cash book for Barzahlungen — § 146 AO, § 22 UStG)
+model KassenbuchEntry {
+  id            String   @id @default(cuid())
+  number        String   @unique // gapless, e.g. KAS-2026-0001
+  date          DateTime
+  type          String   // einnahme|ausgabe
+  description   String
+  amountCents   Int      // signed: + for einnahme, - for ausgabe
+  taxBp         Int?     // USt % (if applicable)
+  taxFree       Boolean  @default(false) // steuerfrei
+  // receipt link
+  belegId       String?  // link to Beleg (Kassenbeleg)
+  // balance after this entry (laufender Kassenstand)
+  balanceCents  Int      @default(0)
+  // GoBD: Kassenbuch ist unveränderlich (elektronische Aufzeichnung)
+  createdAt     DateTime @default(now())
+}