nisse-review: a new head's review waits for its CI

A review judges the CI result (R1), so a new head's review now waits while
its checks are pending, and starts once they finish, passed or failed. It
also keeps reviews off a GPU that CI is using: #154's first review ran
beside CI's end-to-end job and took about 30 minutes.

- Pending: waits up to tuning.review.ci_wait_s (1 h), then reviews anyway.
- No checks: waits tuning.review.ci_grace_s (2 min) for them to appear,
  then reviews.
- A PR waiting on CI holds up no other: the oldest settled one goes first.
- The head's first sighting is kept on the item (seen_at).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

docs/Architecture.md

@@ -888,7 +888,9 @@ else) towards better changes.
 - **A work item per PR,** scoped to its repository (L1). It closes when the PR
   merges or closes.
 - **What starts a run:** the PR becoming ready, a new push, or a new comment or
-  review on it.
+  review on it. A new head's review waits for its checks to finish (passed or
+  failed), so it is judged with the CI result and stays off a GPU that CI is
+  using; up to a tuning limit, and not at all where there is no CI.
 - **The first review** is given the PR (title, description, its commits and diff,
   its comments, and the issue it closes); the reviewer reads the rest as it needs
   it (R3).