fix(pool): keep idle stealing retries on their worker (#3346)

fix(pool): keep idle stealing retries on their worker (#3346)

* fix: account task responses to the replying worker node

Resolve the worker node from the response worker id and re-resolve node keys
after promise continuations and stolen-task delays, since keys shift when
workers are removed.

* refactor(pool): reuse UUID and shared regression helpers

* docs: remove regression helper contribution guidance

* test(pool): unify regression deadlines and message waits

* fix(pool): preserve worker info overrides in task statistics

* docs(api): remove idle retry implementation detail

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Co-authored-by: Jérôme Benoit <jerome.benoit@piment-noir.org>