application/worker.py::mcp_oauth now publishes
authorization_url on the mcp.oauth.awaiting_redirect envelope.
frontend/src/modals/MCPServerModal.tsx consumes it from SSE
instead of polling /oauth_status/<task_id> every 1s.
The URL is generated inside DocsGPTOAuth.redirect_handler when
the FastMCP client triggers OAuth. The worker now plumbs a
publish callback through tool_config -> MCPTool -> DocsGPTOAuth
so the awaiting_redirect publish fires from inside the handler
at the exact point the URL becomes known. The legacy Redis
mcp_oauth_status setex writes and the GET
/api/mcp_server/oauth_status/<task_id> endpoint are kept as
belt-and-suspenders; nothing in the frontend reads them now.