feat(m8): P1 MinIO 对象存储与文件管理

- 迁移 000023 gateway.file_objects(personal/system 归属隔离 + 部分索引)
- internal/platform/storage:minio-go 适配(端点 scheme 剥离、流式 PutObject/Open/Delete)
- internal/workbench/files.go:FileService(sha256 校验、PutObject-then-insert 回滚、delete 先删行再删对象)
- admin /api/v1/admin/files + portal /api/v1/portal/files 处理器(流式上传下载、Content-Disposition)
- RBAC file:read/file:manage;菜单加文件管理 + 门户文件仓库
- compose 增 minio 服务(S3_* anchor、不暴露端口);nginx client_max_body_size 32m→256m
- 管理端文件管理页 + 门户个人文件仓;集成测试 TestFileObjectLifecycle 连真 MinIO 通过
- healthz object_storage:true;README/PRODUCTION/进展文档同步

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

internal/operations/admin_http.go

@@ -48,7 +48,7 @@ func (h *AdminHTTPHandler) systemInfo(w http.ResponseWriter, r *http.Request) {
 		apiresponse.Error(w, http.StatusServiceUnavailable, "系统信息查询失败")
 		return
 	}
-	apiresponse.OK(w, map[string]any{"version": h.version, "go_version": runtime.Version(), "uptime_seconds": int64(time.Since(h.startedAt).Seconds()), "database": "postgresql", "object_storage": false, "clickhouse": false, "enabled_providers": providers, "enabled_models": models, "enabled_api_keys": keys})
+	apiresponse.OK(w, map[string]any{"version": h.version, "go_version": runtime.Version(), "uptime_seconds": int64(time.Since(h.startedAt).Seconds()), "database": "postgresql", "object_storage": true, "clickhouse": false, "enabled_providers": providers, "enabled_models": models, "enabled_api_keys": keys})
 }
 
 func (h *AdminHTTPHandler) overview(w http.ResponseWriter, r *http.Request) {