fix: 云端函数默认注入当前登录用户信息

- 当请求参数未指定 user_id 时，使用 token 中的用户 ID
- 确保 user、subscription、devices 等变量始终有值

backend/internal/router/app/dynamic.go

@@ -173,9 +173,13 @@ func handleExecuteDynamicCode(c *gin.Context) {
 	userVariables := map[string]interface{}{}
 	devices := []map[string]interface{}{}
 
+	targetUserID := claims.UserID
 	if req.UserID != nil {
+		targetUserID = *req.UserID
+	}
+
 	var user model.AppUser
-		if err := database.DB.Where("id = ? AND application_id = ?", *req.UserID, app.ID).First(&user).Error; err == nil {
+	if err := database.DB.Where("id = ? AND application_id = ?", targetUserID, app.ID).First(&user).Error; err == nil {
 		userData = map[string]interface{}{
 			"id":            user.ID,
 			"username":      user.Username,
@@ -217,7 +221,6 @@ func handleExecuteDynamicCode(c *gin.Context) {
 			userVariables[v.VarName] = v.VarValue
 		}
 	}
-	}
 
 	if err := vm.Set("user", userData); err != nil {
 		response.Error(c, 500, "用户数据设置失败")