Replace all hardcoded shortcut key rendering with useShortcutKeys() so
rebound shortcuts always display correctly. Add Cmd+O (new worktree),
Cmd+Shift+Backspace (archive worktree) with proper active-project
scoping. Show shortcut hints in tooltips and dropdown menus. Fix tooltip
alignment to center, bump dropdown menu surface level, simplify
TerminalPane to single-terminal, and add special key display symbols.