feat: Add loot builder backend + static data + DB migration

- Migration 013: loot_profiles table (JSONB loot_table + loot_groups, license-scoped)
- TypeORM entity matching migration schema exactly
- NestJS loot module: 10 endpoints (CRUD, duplicate, apply, import, export, containers)
- Multiplier logic recursively scales Min/Max/Scrap across loot tables and groups
- Apply-to-server writes BetterLoot JSON via NATS file manager + RCON reload
- Frontend static data: 191 Rust items, 51 container prefabs
- TypeScript types for BetterLoot data model (PrefabLoot, LootEntry, LootRNG, etc.)
- Fix vue-tsc errors: UngroupedItems uses LootRNG, null safety in store/view

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend-nest/src/app.module.ts

@@ -35,6 +35,7 @@ import { SetupModule } from './modules/setup/setup.module';
 import { MigrationModule } from './modules/migration/migration.module';
 import { ChangelogModule } from './modules/changelog/changelog.module';
 import { FilesModule } from './modules/files/files.module';
+import { LootModule } from './modules/loot/loot.module';
 
 // Shared Services
 import { NatsService } from './services/nats.service';
@@ -105,6 +106,7 @@ import { NatsBridgeGateway } from './gateways/nats-bridge.gateway';
     MigrationModule,
     ChangelogModule,
     FilesModule,
+    LootModule,
   ],
   providers: [
     // Global guards (order matters: auth first, then license, then permissions)