feat(listings): add user-facing scam/abuse report flow (GOO-19)

- Add ListingFlag model with FlagReason enum (SCAM, DUPLICATE, WRONG_INFO, ALREADY_SOLD, INAPPROPRIATE)
- Add POST /listings/:id/report endpoint with rate limiting and duplicate prevention
- Auto-flag listings with ≥3 reports to PENDING_REVIEW for moderator review
- Add GET /admin/flagged-listings endpoint for admin moderation queue
- Add "Báo cáo" button + modal on listing detail page (Vietnamese UI)
- Add Prisma migration for listing_flags table with unique constraint per user/listing

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

apps/api/src/modules/search/search.module.ts

@@ -1,7 +1,7 @@
 import { Module, type OnModuleInit } from '@nestjs/common';
 import { CqrsModule } from '@nestjs/cqrs';
 import { makeCounterProvider } from '@willsoto/nestjs-prometheus';
-import { LoggerService } from '@modules/shared';
+import { LoggerService, TypesenseClientService } from '@modules/shared';
 import { SubscriptionsModule } from '@modules/subscriptions';
 import { CreateSavedSearchHandler } from './application/commands/create-saved-search/create-saved-search.handler';
 import { DeleteSavedSearchHandler } from './application/commands/delete-saved-search/delete-saved-search.handler';
@@ -21,7 +21,6 @@ import { SavedSearchAlertHandler } from './infrastructure/event-handlers/saved-s
 import { ListingIndexerService } from './infrastructure/services/listing-indexer.service';
 import { PostgresSearchRepository } from './infrastructure/services/postgres-search.repository';
 import { ResilientSearchRepository, SEARCH_DEGRADATION_TOTAL } from './infrastructure/services/resilient-search.repository';
-import { TypesenseClientService } from './infrastructure/services/typesense-client.service';
 import { TypesenseSearchRepository } from './infrastructure/services/typesense-search.repository';
 import { SavedSearchController } from './presentation/controllers/saved-search.controller';
 import { SearchController } from './presentation/controllers/search.controller';
@@ -34,7 +33,6 @@ const QueryHandlers = [SearchPropertiesHandler, GeoSearchHandler, GetSavedSearch
   controllers: [SearchController, SavedSearchController],
   providers: [
     // Infrastructure
-    TypesenseClientService,
     TypesenseSearchRepository,
     PostgresSearchRepository,
     ResilientSearchRepository,
@@ -61,11 +59,10 @@ const QueryHandlers = [SearchPropertiesHandler, GeoSearchHandler, GetSavedSearch
     ...CommandHandlers,
     ...QueryHandlers,
   ],
-  exports: [ListingIndexerService, SEARCH_REPOSITORY, TypesenseClientService],
+  exports: [ListingIndexerService, SEARCH_REPOSITORY],
 })
 export class SearchModule implements OnModuleInit {
   constructor(
-    private readonly typesenseClient: TypesenseClientService,
     private readonly searchRepo: ResilientSearchRepository,
     private readonly logger: LoggerService,
   ) {}