Fix code formatting and linting issues

- Updated GitHub Actions workflow to use correct flake8 configuration
- Fixed line length issues by using 88 characters as configured
- Removed unused imports and trailing whitespace
- Fixed f-string placeholders and unused variables
- All linting checks now pass with project configuration

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

wikijs/auth/base.py

@@ -5,12 +5,12 @@ providing a consistent interface for different authentication methods.
 """
 
 from abc import ABC, abstractmethod
-from typing import Dict, Optional
+from typing import Dict
 
 
 class AuthHandler(ABC):
     """Abstract base class for Wiki.js authentication handlers.
-    
+
     This class defines the interface that all authentication implementations
     must follow, ensuring consistent behavior across different auth methods.
     """
@@ -18,56 +18,54 @@ class AuthHandler(ABC):
     @abstractmethod
     def get_headers(self) -> Dict[str, str]:
         """Get authentication headers for HTTP requests.
-        
+
         Returns:
             Dict[str, str]: Dictionary of headers to include in requests.
-            
+
         Raises:
             AuthenticationError: If authentication is invalid or expired.
         """
-        pass
 
     @abstractmethod
     def is_valid(self) -> bool:
         """Check if the current authentication is valid.
-        
+
         Returns:
             bool: True if authentication is valid, False otherwise.
         """
-        pass
 
     @abstractmethod
     def refresh(self) -> None:
         """Refresh the authentication if possible.
-        
+
         For token-based authentication, this should refresh the token.
         For API key authentication, this is typically a no-op.
-        
+
         Raises:
             AuthenticationError: If refresh fails.
         """
-        pass
 
     def validate_credentials(self) -> None:
         """Validate credentials and refresh if necessary.
-        
+
         This is a convenience method that checks validity and refreshes
         if needed. Subclasses can override for custom behavior.
-        
+
         Raises:
             AuthenticationError: If credentials are invalid or refresh fails.
         """
         if not self.is_valid():
             self.refresh()
-        
+
         if not self.is_valid():
             from ..exceptions import AuthenticationError
+
             raise AuthenticationError("Authentication credentials are invalid")
 
 
 class NoAuth(AuthHandler):
     """No-authentication handler for testing or public instances.
-    
+
     This handler provides an empty authentication implementation,
     useful for testing or when accessing public Wiki.js instances
     that don't require authentication.
@@ -75,7 +73,7 @@ class NoAuth(AuthHandler):
 
     def get_headers(self) -> Dict[str, str]:
         """Return empty headers dict.
-        
+
         Returns:
             Dict[str, str]: Empty dictionary.
         """
@@ -83,7 +81,7 @@ class NoAuth(AuthHandler):
 
     def is_valid(self) -> bool:
         """Always return True for no-auth.
-        
+
         Returns:
             bool: Always True.
         """
@@ -91,7 +89,6 @@ class NoAuth(AuthHandler):
 
     def refresh(self) -> None:
         """No-op for no-auth.
-        
+
         This method does nothing since there's no authentication to refresh.
         """
-        pass