feat: Recurring invoices + license suspend on dunning level 3 (PRD §6.4/§6.6)

- Recurring API: list contracts needing invoicing + run endpoint
- Auto-generate draft invoices for Wartung/SLA + Dienstvertrag contracts
- Automatic license suspension at dunning level 3 (PRD §6.4)
- Recurring billable expenses tracking
- MRR/ARR computation from contracts + expenses
- Prisma: added Contract.company + Expense.company relations
- Scheduler info (pg-boss monthly cron in production)

src/components/aos/app-shell.tsx

@@ -20,6 +20,7 @@ import { LicensesView } from './views/licenses'
 import { ContractsView } from './views/contracts'
 import { ExpensesView } from './views/expenses'
 import { FinanceView } from './views/finance'
+import { RecurringView } from './views/recurring'
 import { AccountingView } from './views/accounting'
 import { AuditView } from './views/audit'
 import { DataView } from './views/data'
@@ -72,6 +73,7 @@ export function AppShell() {
           {view === 'contracts' && <ContractsView />}
           {view === 'expenses' && <ExpensesView />}
           {view === 'finance' && <FinanceView />}
+          {view === 'recurring' && <RecurringView />}
           {view === 'accounting' && <AccountingView />}
           {view === 'audit' && <AuditView />}
           {view === 'data' && <DataView />}