Adds docs/MANUAL-SMOKE-F10.md (clean editor → edit → propose → ✓/✗ →
Annotations toggle → status-bar PUC-6 → theming → cleanliness) following the
F7/F9 smoke format. Adds the F10 "write left / review right" section to the
README feature list and notes F6's two-pane diff and F9's authorship view are
retained only as data layers, not separate user surfaces.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Ben Stull