nisse-review: a stop ends a review in progress; quieter repo failures

SIGTERM used to stop only new rounds: a review in progress ran on until
systemd killed it 90s later. Now the scheduler's stop sets the driver's
cancel flag, so the run ends at its next turn, and a model call in flight
is broken off (Interruptible, raising Stopped from the signal handler, only
ever inside a model call). The item goes back to ready, with nothing
drafted posted and no failure counted; replies already posted carry their
markers and are not repeated.

intake.repo_failed is logged when a repository starts failing or the reason
changes, and intake.repo_ok when it lists again, not every round.

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

nisse-review/tests/test_review.py

@@ -15,6 +15,7 @@ from nisse_core.knowledge.vault import Vault
 from nisse_core.log.canonical import AssistantText
 from nisse_core.loop.driver import Driver
 from nisse_core.oplog import OpLog
+from nisse_core.state.cancel import Cancel
 from nisse_review.access import AccessRefused, check, reviewed
 from nisse_review.build import StartupError, check_access
 from nisse_review.review import Reviewer, _diff_lines, marker
@@ -38,12 +39,13 @@ def world(
 ) -> dict[str, Any]:
     gitea = gitea or FakeGitea(repos={REPO: [pr()]})
     oplog = OpLog("nisse-review", io.StringIO())
+    cancel = more.setdefault("cancel", Cancel())  # the driver's and the scheduler's
     store = StateStore(tmp_path / "state.db", oplog=oplog)
     vault = Vault(tmp_path / "vault", {"memory/nisse-review": "rw"}, agent="r")
     reviewer = Reviewer(
         store,
         gitea,  # type: ignore[arg-type]
-        Driver(model, "m"),  # type: ignore[arg-type]
+        Driver(model, "m", cancel=cancel),  # type: ignore[arg-type]
         account=gitea.account,
         gitea_url="https://gitea.test",
         oplog=oplog,