fix: social login providers now work from DB config without restart

- Extract all OAuth registration into _setup_social_providers() with a
  _register_oauth_client() helper that clears the authlib _clients cache
  so credentials can change without a restart
- Add refresh_social_providers() public function called after every
  settings reload (lifespan startup + settings_sync live reload)
- Fix connections page linked status to use _get_effective() (DB-aware)
  instead of the stale startup-time SOCIAL_PROVIDERS dict
- Fix oauth_configured template variable similarly
- Add tests: DB-driven linked status, stale-provider clearing,
  register_oauth_client cache-clear, refresh function coverage

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/DocuElevate/sessions/ef15910f-fd25-469a-814b-9e1fb40659c9

app/utils/settings_sync.py

@@ -71,6 +71,16 @@ def notify_settings_updated() -> None:
     except Exception as exc:
         logger.warning(f"Could not reload in-process settings: {exc}")
 
+    # Re-register OAuth / social-login providers so that any provider whose
+    # credentials were just saved (or updated) in the database is active
+    # immediately on the login page — no restart required.
+    try:
+        from app.auth import refresh_social_providers
+
+        refresh_social_providers()
+    except Exception as exc:
+        logger.warning(f"Could not refresh social login providers after settings update: {exc}")
+
     # Re-check OCR language availability in the background whenever settings
     # are updated.  This ensures that if a user changes tesseract_language or
     # easyocr_languages via the UI, the new language data is downloaded without