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/shared/infrastructure/index.ts

@@ -14,6 +14,7 @@ export { RedisService } from './redis.service';
 export { RedisIoAdapter } from './redis-io.adapter';
 export { CacheService, CachePrefix, CacheTTL } from './cache.service';
 export { LoggerService } from './logger.service';
+export { TypesenseClientService } from './typesense-client.service';
 export { EventBusService } from './event-bus.service';
 export { GlobalExceptionFilter } from './filters/global-exception.filter';
 export { CorrelationIdMiddleware } from './middleware/correlation-id.middleware';

apps/api/src/modules/shared/infrastructure/typesense-client.service.ts

@@ -0,0 +1,37 @@
+import { Injectable, type OnModuleInit } from '@nestjs/common';
+import { Client as TypesenseClient } from 'typesense';
+import { LoggerService } from './logger.service';
+
+/**
+ * Provides a shared Typesense client for search, indexers, and health probes.
+ * Lives in SharedModule so any feature module can inject it without importing
+ * SearchModule.
+ */
+@Injectable()
+export class TypesenseClientService implements OnModuleInit {
+  private client!: TypesenseClient;
+
+  constructor(private readonly logger: LoggerService) {}
+
+  onModuleInit(): void {
+    this.client = new TypesenseClient({
+      nodes: [
+        {
+          host: process.env['TYPESENSE_HOST'] || 'localhost',
+          port: parseInt(process.env['TYPESENSE_PORT'] || '8108', 10),
+          protocol: process.env['TYPESENSE_PROTOCOL'] || 'http',
+        },
+      ],
+      apiKey: process.env['TYPESENSE_API_KEY'] || 'ts_dev_key_change_me',
+      connectionTimeoutSeconds: 5,
+      retryIntervalSeconds: 0.1,
+      numRetries: 3,
+    });
+
+    this.logger.log('TypesenseClientService initialized', 'TypesenseClient');
+  }
+
+  getClient(): TypesenseClient {
+    return this.client;
+  }
+}

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

@@ -19,6 +19,7 @@ import { RequestLoggingMiddleware } from './infrastructure/middleware/request-lo
 import { SanitizeInputMiddleware } from './infrastructure/middleware/sanitize-input.middleware';
 import { PrismaService } from './infrastructure/prisma.service';
 import { RedisService } from './infrastructure/redis.service';
+import { TypesenseClientService } from './infrastructure/typesense-client.service';
 
 @Global()
 @Module({
@@ -34,6 +35,7 @@ import { RedisService } from './infrastructure/redis.service';
     RedisService,
     CacheService,
     EventBusService,
+    TypesenseClientService,
     makeCounterProvider({
       name: CACHE_HIT_TOTAL,
       help: 'Total number of cache hits',
@@ -54,7 +56,7 @@ import { RedisService } from './infrastructure/redis.service';
       useClass: GlobalExceptionFilter,
     },
   ],
-  exports: [PrismaService, RedisService, CacheService, LoggerService, EventBusService, FieldEncryptionService, PrometheusModule],
+  exports: [PrismaService, RedisService, CacheService, LoggerService, EventBusService, FieldEncryptionService, TypesenseClientService, PrometheusModule],
 })
 export class SharedModule implements NestModule {
   configure(consumer: MiddlewareConsumer): void {