Restores the coverage floor (94.85% → 95.19%). The diff-panel work landed
with diff_view.dart at 59% — the hunk header, the addition/removal/context
line rows, the new/deleted/renamed/binary metadata, and the error and
empty-state branches were never exercised. Adds four widget tests over an
injected controller; diff_view.dart goes 59% → 96%.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
jpmschweitzerandClaude Opus 4.8
bc81b0561e