- Added `SettingsList` section-focus state with `sectionFocused`, `hasSectionFocusTargets`, and `toggleSectionFocus()`.
- Implemented section-heading navigation with Tab/Shift+Tab, Up/Down focus jumps, and Enter/Escape exits.
- Updated `/settings` input hints and fallback routing to tab-bar keys when section focus is unavailable.
- Added tests for section-focus navigation, mouse parsing, and tab-bar behavior coverage.