certs: async renewal via background task + status polling

- POST /acme/renew returns a request_id and spawns a background task
  (renew/deploy/refresh steps); dedups per-domain like issue
- completes as "skipped" when acme.sh reports the renewal window
  has not been reached (no --force)
- new GET /acme/renew/status endpoint (iface + handler + blueprint)
- run acme.sh subprocesses off the event loop (asyncio.to_thread)
  in both issuance and renewal
- ActionCell: busy/busyLabel props; certs page disables the Renew
  button and polls renewal status with toasts for success/skip/fail

daemon/iface.py

@@ -121,6 +121,7 @@ POST_ACME_VALIDATE: Endpoint = _ep("POST", "/acme/validate")
 POST_ACME_ISSUE: Endpoint = _ep("POST", "/acme/issue")
 GET_ACME_ISSUE_STATUS: Endpoint = _ep("GET", "/acme/issue/status")
 POST_ACME_RENEW: Endpoint = _ep("POST", "/acme/renew")
+GET_ACME_RENEW_STATUS: Endpoint = _ep("GET", "/acme/renew/status")
 DELETE_ACME_REMOVE: Endpoint = _ep("DELETE", "/acme/remove")
 POST_ACME_EMAIL: Endpoint = _ep("POST", "/acme/email")
 GET_ACME_EMAIL: Endpoint = _ep("GET", "/acme/email")