fix(mining-service): 修正 AdminController 路由前缀

将 AdminController 路由从 /admin 改为 /mining/admin，
以匹配 Kong 网关路由 /api/v2/mining

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/mining-service/src/api/controllers/admin.controller.ts

@@ -8,7 +8,7 @@ import { BatchMiningService, BatchMiningItem, BatchMiningRequest } from '../../a
 import { Public } from '../../shared/guards/jwt-auth.guard';
 
 @ApiTags('Admin')
-@Controller('admin')
+@Controller('mining/admin')
 export class AdminController {
   constructor(
     private readonly prisma: PrismaService,