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/main.py

@@ -189,6 +189,18 @@ async def lifespan(app: FastAPI):
     finally:
         db.close()
 
+    # Re-register OAuth / social-login providers now that DB settings are
+    # loaded.  auth.py runs its initial registration at import time (before
+    # the lifespan runs), so providers that are only configured in the
+    # database would not be registered yet.  Calling refresh here ensures
+    # they are active immediately on startup without any manual restart.
+    try:
+        from app.auth import refresh_social_providers
+
+        refresh_social_providers()
+    except Exception as e:
+        logging.warning(f"Could not refresh social login providers on startup: {e}")
+
     # Initialize Sentry after DB settings are loaded so that values configured
     # via the database UI (e.g. SENTRY_DSN) are respected in addition to env vars.
     init_sentry()