keybar:
- add Ctrl+R (搜历史/\x12), Ctrl+L (重绘/\x0c), Ctrl+D (退出/\x04)
- each key now shows a short function caption under the glyph (self-documenting
on touch where tooltips don't appear); 17 keys total
- test/keybar.test.ts updated to 17 keys
cheat-sheet (new public/shortcuts.ts):
- ⌨ toolbar button opens a grouped reference of common Claude Code shortcuts
(general / editing / multiline / macOS / prefixes), each labeled with what it
does; keys also on the bottom bar are tagged 键栏
- Esc / click-outside to close; styled card with sticky header + accent tags
216 tests green; tsc + build clean.
