Add src/diff.ts: a reusable unified-diff engine that parses diffs into
per-file +/− stats and filters noise (lockfiles, minified/generated
assets, source maps, snapshots, build output, node_modules/vendor,
binary/media) so review prompts feed only clean, review-relevant changes.
Exports DiffSummary/FileDiff shapes, EXCLUDED_PATTERNS, isExcluded,
parseDiff, plus filterNoise and configurable extra-pattern/ignore-path
overrides. Malformed diff chunks are skipped without crashing, and
excluded files are never double-counted into totals.
Add tests/diff.test.ts covering the included/excluded split, per-file
+/− counts, totals excluding noise, malformed-chunk guard, and the
noise-filter override rules.
Michael Freno
88f6b4df93