refactor(backend): Extract Airtable token refresh to shared utility

- Create app/utils/airtable_token_utils.py for token refresh logic
- Update all connectors to use centralized token refresh function
- Affected connectors: airtable, clickup, confluence, discord, jira, notion, slack, teams
- Improves code reusability and maintainability
- No functional changes, pure refactoring

surfsense_backend/app/connectors/teams_connector.py

@@ -16,7 +16,6 @@ from sqlalchemy.future import select
 
 from app.config import config
 from app.db import SearchSourceConnector
-from app.routes.teams_add_connector_route import refresh_teams_token
 from app.schemas.teams_auth_credentials import TeamsAuthCredentialsBase
 from app.utils.oauth_security import TokenEncryption
 
@@ -146,6 +145,8 @@ class TeamsConnector:
                     )
 
                 # Refresh token
+                # Lazy import to avoid circular dependency
+                from app.routes.teams_add_connector_route import refresh_teams_token
                 connector = await refresh_teams_token(self._session, connector)
 
                 # Reload credentials after refresh