fix(mining-admin): APK下载URL指向localhost导致手机无法下载

问题：FileStorageService 默认 UPLOAD_BASE_URL 为 http://localhost:3020/downloads，
手机端无法访问服务器的 localhost。

修复：
- docker-compose.2.0.yml: 添加 UPLOAD_BASE_URL=https://rwaapi.szaiai.com/mining-admin/downloads
- 添加 mining-admin-uploads volume 持久化上传的 APK 文件
- 修正默认端口 3020→3023（mining-admin-service 实际端口）

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

backend/services/docker-compose.2.0.yml

@@ -158,6 +158,11 @@ services:
       TRADING_SERVICE_URL: http://trading-service:3022
       AUTH_SERVICE_URL: http://auth-service:3024
       JWT_SECRET: ${ADMIN_JWT_SECRET:-your-admin-jwt-secret-change-in-production}
+      # APK 下载地址前缀（通过 Kong 网关 /mining-admin 路由访问）
+      UPLOAD_BASE_URL: https://rwaapi.szaiai.com/mining-admin/downloads
+      UPLOAD_DIR: ./uploads
+    volumes:
+      - mining-admin-uploads:/app/uploads
     ports:
       - "3023:3023"
     healthcheck:
@@ -336,6 +341,10 @@ services:
 # =============================================================================
 # 网络配置 - 连接到 1.0 的网络以共享基础设施
 # =============================================================================
+volumes:
+  mining-admin-uploads:
+    driver: local
+
 networks:
   rwa-network:
     external: true

backend/services/mining-admin-service/src/infrastructure/storage/file-storage.service.ts

@@ -20,7 +20,7 @@ export class FileStorageService {
 
   constructor(private readonly configService: ConfigService) {
     this.uploadDir = this.configService.get<string>('UPLOAD_DIR', './uploads')
-    this.baseUrl = this.configService.get<string>('UPLOAD_BASE_URL', 'http://localhost:3020/downloads')
+    this.baseUrl = this.configService.get<string>('UPLOAD_BASE_URL', 'http://localhost:3023/downloads')
 
     // 确保上传目录存在
     this.ensureUploadDir()