Implement OAuth login with Authentik integration, update user management, and enhance team functionalities

- Added OAuth login functionality using Authentik, allowing users to log in via OpenID.
- Updated user registration and login processes to handle OAuth users.
- Enhanced team management features, including joining and leaving teams, and displaying user-specific team information.
- Improved error handling and user feedback for team actions.
- Added new database migrations for OAuth-related fields in the users table.
- Updated templates to reflect changes in user authentication and team management.
- Refactored dashboard and leaderboard views to include user context and team memberships.

app/templates/auth/login.html

@@ -78,7 +78,7 @@
       <p class="text-center text-gray-600 mb-4">Or sign in with</p>
       <div class="flex justify-center">
         <a href="/auth/oauth-login" class="bg-blue-600 text-white py-2 px-4 rounded-md hover:bg-opacity-90 transition w-full flex items-center justify-center">
-          <i class="fas fa-sign-in-alt mr-2"></i> {{ oauth_provider_name }}
+          <i class="fas fa-sign-in-alt mr-2"></i> Authentik
         </a>
       </div>
     </div>