M7.3: nisse-review's first slice

A new package over nisse-core: it reviews every ready PR in the
repositories its account can read, and posts one COMMENT review.

- scheduler: each round, open PRs per readable repository (or the
  configured repositories); an item per PR, ready unless draft or WIP;
  closed with the PR. One review at a time, oldest first.
- reader: the repository at head and base from Gitea archives, unpacked
  and read in Python (read_file, list_files, search_code), and its issues;
  bound to the item's repository; no git, no shell.
- review: starts from the PR, commits, diff, comments, closed issues, CI;
  comment drafts a point on any existing line; post_review posts one
  COMMENT review at the head, inline where Gitea takes it, else as links in
  the summary. ask_expert; vault and memory (memory/nisse-review).
- L8: posting is an intent; recovery asks Gitea for the marked review and
  never posts twice; with Gitea down, the item waits.
- Failures retried, then said on the PR until the next push.
- Startup refuses an account that can push to or administer any repo.
- nisse-core gitea: readable_repositories, open_pull_requests, diff,
  commits, archive, issue, search_issues, reviews, post_review; PR fields.
- Bring-up: scripts/review-bringup.sh; nisse-review.example.yaml.
- Tests: unit over a fake Gitea and scripted model; a live test
  (NISSE_REVIEW_GITEA_TOKEN) reviews a PR in a fresh test repository.
- Docs: Development Plan M7.3, Tuning Guide (tuning.review.*).

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

nisse-review/src/nisse_review/main.py

@@ -0,0 +1,44 @@
+"""Entry point for the review agent: loads its configuration, checks its
+access, and reviews until told to stop."""
+
+import os
+import signal
+import sys
+from pathlib import Path
+from types import FrameType
+
+from nisse_core.config import ConfigError
+from nisse_core.envfile import load_env_file
+from nisse_review.build import StartupError, build
+from nisse_review.config import ReviewConfig
+
+
+def main() -> int:
+    load_env_file(Path(os.environ.get("NISSE_ENV", ".env")).expanduser())
+    try:
+        config = ReviewConfig.load()
+        built = build(config)
+    except (ConfigError, StartupError) as exc:
+        print(f"nisse-review: {exc}", file=sys.stderr)
+        return 2
+
+    def shutdown(_signum: int, _frame: FrameType | None) -> None:
+        print("nisse-review: stopping", file=sys.stderr)
+        built.scheduler.stop()
+
+    signal.signal(signal.SIGINT, shutdown)
+    signal.signal(signal.SIGTERM, shutdown)
+    print(
+        f"nisse-review: ready as {built.account}, reading "
+        + (", ".join(built.repositories) or "no repositories"),
+        file=sys.stderr,
+    )
+    try:
+        built.scheduler.run_forever()
+    finally:
+        built.close()
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())