fix(admin-service): update MinIO default endpoint to oss.gogenex.com

将 FileStorageService 的默认连接参数从 localhost 更新为生产域名：
- endPoint 默认值: localhost → oss.gogenex.com
- port 默认值: 9000 → 443
- useSSL 默认值: false → true（?? 运算符保证未设置时默认开启）
- accessKey/secretKey 默认值更新为生产凭证

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/services/admin-service/src/application/services/file-storage.service.ts

@@ -11,11 +11,11 @@ export class FileStorageService {
 
   constructor() {
     this.minio = new MinioClient({
-      endPoint: process.env.MINIO_ENDPOINT || 'localhost',
-      port: parseInt(process.env.MINIO_PORT || '9000', 10),
-      useSSL: process.env.MINIO_USE_SSL === 'true',
-      accessKey: process.env.MINIO_ACCESS_KEY || 'minioadmin',
-      secretKey: process.env.MINIO_SECRET_KEY || 'minioadmin',
+      endPoint: process.env.MINIO_ENDPOINT || 'oss.gogenex.com',
+      port: parseInt(process.env.MINIO_PORT || '443', 10),
+      useSSL: (process.env.MINIO_USE_SSL ?? 'true') === 'true',
+      accessKey: process.env.MINIO_ACCESS_KEY || 'genex-admin',
+      secretKey: process.env.MINIO_SECRET_KEY || 'genex-minio-secret',
     });
   }