fix(mcp): Refresh expired OAuth tokens before tool discovery

The discover_tools endpoint was reading raw access tokens from stored
credentials without checking if they had expired. This caused users
to be prompted to re-authenticate every time the token expired (~1h).

Now uses creds_manager.refresh_if_needed() to transparently refresh
expired tokens before using them.

autogpt_platform/backend/backend/api/features/mcp/routes.py

@@ -98,6 +98,8 @@ async def discover_tools(
                     ):
                         best_cred = cred
             if best_cred:
+                # Refresh the token if expired before using it
+                best_cred = await creds_manager.refresh_if_needed(user_id, best_cred)
                 logger.info(
                     f"Using MCP credential {best_cred.id} for {request.server_url}, "
                     f"expires_at={best_cred.access_token_expires_at}"