feat(cache): implement Redis caching layer for hot-read endpoints

Add cache-aside pattern for listing detail, search results, market
analytics (4 endpoints), and user profile queries. Cache invalidation
on all write mutations. Prometheus cache_hit_total/cache_miss_total
metrics with resource labels.

- CacheService: getOrSet, invalidate, invalidateByPrefix (SCAN-based)
- TTLs: listing 5m, search 1m, market 30m, profile 10m
- All 230 tests passing (13 new cache tests + 6 updated handler tests)

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

apps/api/src/modules/shared/infrastructure/index.ts

@@ -1,5 +1,6 @@
 export { PrismaService } from './prisma.service';
 export { RedisService } from './redis.service';
+export { CacheService, CachePrefix, CacheTTL } from './cache.service';
 export { LoggerService } from './logger.service';
 export { EventBusService } from './event-bus.service';
 export { GlobalExceptionFilter } from './filters/global-exception.filter';