Integrate Qiniu upload service and update configuration

- Added Qiniu configuration options to .env.example and config.go for file uploads.
- Refactored main.go to include new Qiniu service and upload handler.
- Updated route registration to accommodate the new upload handler.
- Enhanced documentation to include references for Qiniu upload functionality.
- Removed legacy authentication handler and services to streamline the codebase.

internal/routes/common_routes.go

@@ -0,0 +1,16 @@
+package routes
+
+import (
+	"github.com/gin-gonic/gin"
+
+	commonhandler "wx_service/internal/common/handler"
+)
+
+func registerCommonRoutes(protected *gin.RouterGroup, uploadHandler *commonhandler.UploadHandler) {
+	// 公共接口（所有小程序共用）
+	common := protected.Group("/common")
+	{
+		// 七牛直传凭证：前端先拿 token，再直传文件到七牛 upload_url
+		common.POST("/upload/qiniu/token", uploadHandler.QiniuToken)
+	}
+}