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/utils/auth.py

@@ -35,7 +35,7 @@ def generate_token(user_id: int, username: str, role: str = 'user', token_versio
             'sub': username,
             'user_id': user_id,
             'role': role,
-            'token_version': token_version,  # 用于单一客户端登录控制
+            'token_version': token_version,  # For single client login control
         }
         return jwt.encode(
             payload,
@@ -60,12 +60,12 @@ def verify_token(token: str) -> dict:
     try:
         payload = jwt.decode(token, Config.SECRET_KEY, algorithms=['HS256'])
         
-        # 验证 token_version（单一客户端登录控制）
+        # Verify token_version (single client login control)
         user_id = payload.get('user_id')
         token_version = payload.get('token_version')
         
         if user_id and token_version is not None:
-            # 检查数据库中的 token_version 是否匹配
+            # Check if token_version in database matches
             if not _verify_token_version(user_id, token_version):
                 logger.debug(f"Token version mismatch for user {user_id}: expected current, got {token_version}")
                 return None
@@ -81,12 +81,12 @@ def verify_token(token: str) -> dict:
 
 def _verify_token_version(user_id: int, token_version: int) -> bool:
     """
-    验证 token 版本是否与数据库中存储的版本匹配。
-    用于实现单一客户端登录（踢出重复登录）。
+    Verify that the token version matches the version stored in the database.
+    Used to implement single client login (kick out duplicate logins).
     
     Args:
-        user_id: 用户ID
-        token_version: Token中的版本号
+        user_id: user ID
+        token_version: version number in Token
     
     Returns:
         True if version matches, False otherwise
@@ -109,7 +109,7 @@ def _verify_token_version(user_id: int, token_version: int) -> bool:
             return int(token_version) == int(db_token_version)
     except Exception as e:
         logger.error(f"_verify_token_version failed: {e}")
-        # 如果验证失败，为了安全起见，返回 False
+        # If validation fails, for security reasons, return False
         return False