* fix(task): claim awaiting_pm_review without transitioning to claimed
An ownerless awaiting_pm_review task was claimed by the dispatcher (before
spawning the PM) via the transitioning claim, moving it to 'claimed'. The PM's
complete() requires awaiting_pm_review, so it could never complete — observed
live: complete() rejected (invalid_state), task then bounced to blocked. Treat
awaiting_pm_review as the review state it is: claim_task_for_agent now does a
no-transition review-claim for it (mirroring QA/Doc), assigning the owner while
keeping the status. All other states transition as before.
* refactor(task): extract review-claim helper to keep claim_task_for_agent under xenon B
The awaiting_pm_review branch pushed claim_task_for_agent to cyclomatic rank C
(gate requires <= B). Extract the no-transition review-claim into
_claim_review_state; behaviour unchanged, tests still green.
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Co-authored-by: Renn F <rennf93@users.noreply.github.com>
