Refactor and translate comments and docstrings in utility modules to English for better clarity and maintainability. Update Gunicorn and application startup messages for consistency in language. Enhance documentation with English translations for better accessibility.

backend_api_python/app/services/user_service.py

@@ -189,13 +189,13 @@ class UserService:
     
     def get_token_version(self, user_id: int) -> int:
         """
-        获取用户当前的 token 版本号。
+        Get the user's current token version number.
         
         Args:
-            user_id: 用户ID
+            user_id: user ID
         
         Returns:
-            当前 token 版本号，默认为 1
+            Current token version number, default is 1
         """
         try:
             with get_db_connection() as db:
@@ -215,19 +215,19 @@ class UserService:
     
     def increment_token_version(self, user_id: int) -> int:
         """
-        递增用户的 token 版本号，使旧的 token 失效。
-        用于实现单一客户端登录（踢出其他设备）。
+        Increment the user's token version number and invalidate the old token.
+        Used to implement single client login (kick out other devices).
         
         Args:
-            user_id: 用户ID
+            user_id: user ID
         
         Returns:
-            新的 token 版本号
+            New token version number
         """
         try:
             with get_db_connection() as db:
                 cur = db.cursor()
-                # 递增 token_version
+                # Increment token_version
                 cur.execute(
                     """
                     UPDATE qd_users 
@@ -238,7 +238,7 @@ class UserService:
                 )
                 db.commit()
                 
-                # 获取新的 token_version
+                # Get new token_version
                 cur.execute(
                     "SELECT token_version FROM qd_users WHERE id = ?",
                     (user_id,)