fix: clear recovery state on requeue_task to unblock retryable:false tasks

requeue_task removed the task from the dispatched set and approved
preflight, but never cleared the recovery failure counter. Tasks that
hit max retries (retryable: false) could never be re-dispatched even
after the underlying issue was fixed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>