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/store/aos.ts

@@ -16,6 +16,7 @@ export type ViewId =
   | 'contracts'
   | 'expenses'
   | 'finance'
+  | 'recurring'
   | 'accounting'
   | 'audit'
   | 'data'