feat(backend): implement custom middleware for session management and context handling

backend/middleware/context.go

@@ -0,0 +1,28 @@
+package middleware
+
+import (
+	"github.com/labstack/echo/v4"
+)
+
+// CustomContext 扩展 echo.Context 以添加自定义功能
+type CustomContext struct {
+	echo.Context
+	Auth interface{}
+}
+
+// NewCustomContext 创建自定义上下文的构造函数
+func NewCustomContext(c echo.Context) *CustomContext {
+	return &CustomContext{
+		Context: c,
+	}
+}
+
+// ContextMiddleware 中间件用于将标准 echo.Context 转换为 CustomContext
+func ContextMiddleware() echo.MiddlewareFunc {
+	return func(next echo.HandlerFunc) echo.HandlerFunc {
+		return func(c echo.Context) error {
+			cc := NewCustomContext(c)
+			return next(cc)
+		}
+	}
+}