feat(lifecycle): add billing lifecycle with auto-suspend/delete

- New AppLifecycleService with cron-based scanner (60s interval)
- State machine: ACTIVE → SUSPENDED → PENDING_DELETION → DELETED
- Auto-renew hourly plans from wallet
- Admin-configurable grace periods via PlatformSettings table
- New LifecycleController (GET/PATCH /lifecycle/settings)
- PlatformSetting entity for runtime admin config
- BillingService: calculateCostForApp, deductWallet
- Application entity: planId, billingCycle, lifecycleStatus, planExpiresAt
- New enums: AppLifecycleStatus, BillingCycle

backend/src/app.module.ts

@@ -12,6 +12,7 @@ import { BuildModule } from './build/build.module';
 import { TicketsModule } from './tickets/tickets.module';
 import { BillingModule } from './billing/billing.module';
 import { SnapshotsModule } from './snapshots/snapshots.module';
+import { LifecycleModule } from './lifecycle/lifecycle.module';
 import configuration from './config/configuration';
 
 @Module({
@@ -62,6 +63,7 @@ import configuration from './config/configuration';
     TicketsModule,
     BillingModule,
     SnapshotsModule,
+    LifecycleModule,
   ],
 })
 export class AppModule {}