Replace manual titlebar/drag handler with ModalShell, move Merge button to footer, convert StaticResource token attrs to DynamicResource, snap font sizes to tokens, use MonoFont DynamicResource, and fold tint color literals to RunningTintBrush/ErrorTintBrush.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
- Count additions/deletions per file as lines are parsed.
- Surface load failures and empty-diff states via StatusMessage.
- Pass the worktree base commit so diffs render against the branch
base, not just the working-tree HEAD.