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/auth/application/commands/verify-kyc/verify-kyc.handler.ts

@@ -1,5 +1,6 @@
 import { CommandHandler, type ICommandHandler } from '@nestjs/cqrs';
 import { Inject, NotFoundException } from '@nestjs/common';
+import { CacheService, CachePrefix } from '@modules/shared/infrastructure/cache.service';
 import { VerifyKycCommand } from './verify-kyc.command';
 import { USER_REPOSITORY, type IUserRepository } from '../../../domain/repositories/user.repository';
 
@@ -7,6 +8,7 @@ import { USER_REPOSITORY, type IUserRepository } from '../../../domain/repositor
 export class VerifyKycHandler implements ICommandHandler<VerifyKycCommand> {
   constructor(
     @Inject(USER_REPOSITORY) private readonly userRepo: IUserRepository,
+    private readonly cache: CacheService,
   ) {}
 
   async execute(command: VerifyKycCommand): Promise<void> {
@@ -17,5 +19,7 @@ export class VerifyKycHandler implements ICommandHandler<VerifyKycCommand> {
 
     user.updateKycStatus(command.kycStatus, command.kycData);
     await this.userRepo.update(user);
+
+    await this.cache.invalidate(CacheService.buildKey(CachePrefix.USER_PROFILE, command.userId));
   }
 }