Closes the architect-side gap: the auto-claim daemon wakes implementers on
new tasks, but the architect had no signal when an implementer submitted.
`agenthub watch --await-review` exits (after printing) the moment a task
enters `review` — including any task already in review on connect (initial
check) — so the architect can run it in the background and be re-invoked by
the harness the instant a submission needs a verdict.
- watch.ts: awaitReview option, initial fetchReviewTasks() check + SSE exit
on task→review.
- index.ts: --await-review flag.
- tests: returns immediately on already-pending review; exits on a review
transition while watching. 121/121 green.
Bump 0.4.0 -> 0.5.0.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>