refactor(api): separate Yggdrasil routes from v1 API group

Move Yggdrasil API endpoints from /api/v1/yggdrasil to /api/yggdrasil for
better route organization and compatibility with standard Yggdrasil protocol.
Also upgrade Go to 1.25, update dependencies, and migrate email package from
jordan-wright/email to gopkg.in/mail.v2. Remove deprecated UUID design plan.

internal/handler/routes.go

@@ -52,7 +52,8 @@ func RegisterRoutesWithDI(router *gin.Engine, c *container.Container) {
 	h := NewHandlers(c)
 
 	// API路由组
-	v1 := router.Group("/api/v1")
+	apiGroup := router.Group("/api")
+	v1 := apiGroup.Group("/v1")
 	{
 		// 认证路由（无需JWT）
 		registerAuthRoutes(v1, h.Auth)
@@ -69,15 +70,16 @@ func RegisterRoutesWithDI(router *gin.Engine, c *container.Container) {
 		// 验证码路由
 		registerCaptchaRoutesWithDI(v1, h.Captcha)
 
-		// Yggdrasil API路由组
-		registerYggdrasilRoutesWithDI(v1, h.Yggdrasil)
-
 		// CustomSkinAPI 路由
 		registerCustomSkinRoutes(v1, h.CustomSkin)
 
 		// 管理员路由（需要管理员权限）
 		registerAdminRoutes(v1, c, h.Admin)
 	}
+
+	// Yggdrasil API路由组（独立于v1，路径为 /api/yggdrasil）
+
+	registerYggdrasilRoutesWithDI(apiGroup, h.Yggdrasil)
 }
 
 // registerAuthRoutes 注册认证路由