The checkbox read "Clear saved API key (disable pool first)", but the
panel never defines "pool" and saving with it ticked on an enabled worker
was rejected by the backend.
- Disable the checkbox while the worker is enabled, with a tooltip saying
to turn the worker off first. Also disable it when no key is saved.
- Use "worker" instead of "pool" in user-facing serverless errors, the
serverless guide and the README entry.
Retain durable reservations until provider termination or explicit recovery, protect unresolved pools and credentials, and add scoped reconciliation. Consolidate lifecycle and secret policies and split prompt/media stages with regression coverage.