fix(review): fail closed on incomplete coverage

[pierrick-fonquerne]

What changed

• add a deterministic INCOMPLETE team verdict whenever coverage gaps remain or the 15-finding verification cap leaves findings unchecked
• keep NEEDS_WORK authoritative when a confirmed critical finding is already known
• render fail-closed results when no textual patch or no synthesis is available
• paginate global bot-comment discovery across every issue-comment page
• group inline findings by location and upsert them with stable mode/head/location markers
• delete stale and duplicate inline bot comments within the same mode and head scope
• update the reviewer documentation with the new verdict and rerun semantics

Why

The coverage work in #33 and #34 made every unreviewed input visible, but the global verdict could still say SHIP after partial coverage. Re-running a review also created duplicate inline comments, a global marker beyond GitHub's first comment page could be missed, and inline findings that disappeared on a later run remained visible.

Impact

A partial review can no longer be presented as shippable. Re-runs on the same head commit converge the global and inline bot comments to the current result: existing comments are updated, new locations are created, and results no longer confirmed by that mode are removed.

Validation

• cargo fmt --manifest-path tools/ai-review/Cargo.toml -- --check
• cargo clippy --manifest-path tools/ai-review/Cargo.toml --all-targets -- -D warnings
• cargo test --manifest-path tools/ai-review/Cargo.toml
• Rust 1.88: tests and Clippy/check strict
• 57 Rust tests and 5 workflow policy tests pass
• HTTP integration fixtures cover page-2 updates and empty-result stale deletion
• real multi-batch/idempotence smoke: lightshuttle#316, run 31614721376

Merge policy

Keep this pull request in draft until CI, the real rerun/idempotence smoke test, and review are complete. Do not merge without explicit approval.

[pierrick-fonquerne]

Final smoke validation passed on lightshuttle run 31614721376 against exact SHA 4a55945c74571ba6414838297dd2b28af13dddfb.

• a 38-finding synthesis capped at 15 rendered INCOMPLETE instead of SHIP;
• the seed job created scoped stale inline comment 3768039640, and the team upsert deleted it through the real GitHub API;
• the review mode created three scoped inline comments on the current head, then a same-SHA rerun with zero inline findings removed all three;
• global bot comment IDs remained stable across reruns;
• team, review, and describe jobs completed successfully.

The temporary PR will be closed without merge and cleaned up.