feat(analytics): integrate AI/ML services — AVM endpoint, moderation pipeline, market index cron

- Add AiServiceClient HTTP client for Python FastAPI AI service with timeout and fallback
- Add HttpAVMService that calls Python AVM endpoint, falls back to PrismaAVMService on failure
- Add ListingCreatedModerationHandler: auto-flags suspicious listings via AI moderation on create
- Add MarketIndexCronService: daily cron job aggregating market stats per district/city/type
- Wire ScheduleModule and new providers into AnalyticsModule and AppModule
- Add unit tests for AiServiceClient, HttpAVMService, and moderation handler (all passing)

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/package.json

@@ -23,6 +23,7 @@
     "@nestjs/jwt": "^11.0.2",
     "@nestjs/passport": "^11.0.5",
     "@nestjs/platform-express": "^11.0.0",
+    "@nestjs/schedule": "^6.1.1",
     "@nestjs/swagger": "^11.2.6",
     "@nestjs/terminus": "^11.1.1",
     "@nestjs/throttler": "^6.5.0",