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

src/store/aos.ts

@@ -18,6 +18,7 @@ export type ViewId =
   | 'finance'
   | 'recurring'
   | 'accounting'
+  | 'finanzamt'
   | 'audit'
   | 'data'
   | 'api'