Range and commit modes filter changed files with the working tree's ignore rules #1487

In --from/--to and --commit modes, ignore rules are read from the current checkout, not from the reviewed ref (internal/diff/git.go, partitionDiffs). A local, uncommitted .gitignore entry (or one that exists on the checked-out branch but not on the reviewed one) can drop files from a range review.

Repro: feature adds gen.go and has no .gitignore; with an uncommitted local .gitignore containing gen.go, ocr review --from base --to feature reviews nothing.

Should range/commit modes read .gitignore files from the reviewed ref (e.g. git show REF:.gitignore / check-ignore against a temporary index), or is the working-tree behavior intended?

Environment: v1.12.7.

AI disclosure: found with Claude Code (model: Claude Opus 5) during an audit where each finding was reproduced by a failing test.