feat: Data Management (DSGVO Art. 15/20/30 — export, inventory, retention)

- Data Management API: inventory (Art. 30 Verarbeitungsverzeichnis) + export
- JSON export with SHA-256 checksum (GoBD Jahresarchiv)
- CSV export (DATEV/Excel-compatible)
- Export history (audit-logged)
- Retention periods (8/6 years per GoBD)
- Art. 17 erasure notice (pseudonymization, legal precedence)
- 159 records across 10 categories with legal basis per category

src/components/aos/app-shell.tsx

@@ -22,6 +22,7 @@ import { ExpensesView } from './views/expenses'
 import { FinanceView } from './views/finance'
 import { AccountingView } from './views/accounting'
 import { AuditView } from './views/audit'
+import { DataView } from './views/data'
 import { KbView } from './views/kb'
 import { ApiView } from './views/api'
 import { SettingsView } from './views/settings'
@@ -73,6 +74,7 @@ export function AppShell() {
           {view === 'finance' && <FinanceView />}
           {view === 'accounting' && <AccountingView />}
           {view === 'audit' && <AuditView />}
+          {view === 'data' && <DataView />}
           {view === 'kb' && <KbView />}
           {view === 'api' && <ApiView />}
           {view === 'settings' && <SettingsView />}