fix(review): exit code reflects filtered findings (#312)

[ajianaz]

Summary

Fixes #312 — cora review exits code 2 despite valid SARIF and zero blocking findings on larger diffs.

Root cause

should_block was computed by the engine using config.hook.min_severity. The exit-code logic then used the same should_block flag without re-checking against the filtered issue list (after CLI --severity filtering).

So when a Major finding existed but the user passed --severity critical, the filtered output shown to the user had 0 findings, yet cora review still exited 2 (EXIT_BLOCKED) because should_block was still true. This broke required-status-check CI configs.

Changes

src/commands/review.rs

• Recompute should_block on filtered_response after severity filtering, in both the single-chunk path and the --auto-chunk path. Exit code now matches what the user sees.
• Extracted exit-code decision into a pure helper compute_exit_code(gate_status, ci, filtered_response, hook_mode) — no hidden state, easy to test.
• Added 8 unit tests covering: gate pass/fail override, CI mode with 0 vs ≥1 findings, hook block vs non-block, and the core regression (bug: cora review exits code 2 despite valid SARIF and zero blocking findings (larger diffs) #312) where filtered issues are empty.

Tests

• 8 new unit tests in src/commands/review.rs.
• cargo test commands::review — 8/8 pass.
• cargo clippy -- -D warnings clean, cargo fmt applied.

Versioning

Patch bump 0.6.0 → 0.6.1 (shares the release with #316 and #313).

⚠️ Merge note: CHANGELOG and Cargo.toml will conflict with #317 (scan fix) and the upcoming #313 PR. Suggested merge order: #317 → this PR → #313. The conflicts are confined to the ## [0.6.1] block of CHANGELOG.md and the version line in Cargo.toml/Cargo.lock.

Checklist

• cargo test passes
• cargo clippy -- -D warnings clean
• cargo fmt applied
• CHANGELOG entry under ## [0.6.1] → ### Fixed — Review
• Version bumped in Cargo.toml + Cargo.lock