memory: observe review-thread resolutions that arrive without a new push

[senamakel]

Follow-up from #131. Review outcomes (fixed / rejected / dismissed / disputed) are observed only when a review runs, so a maintainer resolving a thread after the last push is not remembered until the next review of that pull request. GitHub emits no webhook for a thread resolution (see docs/triggers.md), so this needs a product decision: a lightweight observe-only path (poll open PRs' threads on a schedule, or on closed/merged events) versus a full re-review. Raised in #131 (comment).

Co-authored-by: Medulla medulla@tinyhumans.ai

[tinysweeper]

#132: memory — review-thread resolutions that arrive without a new push are not currently observed; needs a product decision (polling or alternative).

Labelled priority: p3.

[senamakel]

Current-source triage (2026-09-14): valid but intentionally awaiting a product decision. GitHub has no review-thread-resolution webhook, so an observe-only scheduled/closure-event poll and a full re-review have materially different cost and semantics. No safe default implementation to choose on the issue’s behalf; leaving open.