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.

scripts/generate_test_account.py

@@ -241,7 +241,7 @@ curl -X POST http://localhost:8080/api/v1/user/yggdrasil-password/reset \\
   -H 'Authorization: Bearer {user_info['jwt_token']}'
 
 # 4. Yggdrasil认证
-curl -X POST http://localhost:8080/api/v1/yggdrasil/authserver/authenticate \\
+curl -X POST http://localhost:8080/api/yggdrasil/authserver/authenticate \\
   -H 'Content-Type: application/json' \\
   -d '{{
     "username": "{user_info['username']}",