- Add switch_context_surface shortcut (default Cmd/Ctrl + 1..9, 0 for the 10th
surface) that opens/closes/switches context panel rail surfaces by their
visible order, configurable and persisted in Settings -> Shortcuts.
- Show order-number badges on rail icons while the modifier is held >500ms;
dismiss on release, blur, or a number press until the next press-and-hold.
- Remove the legacy mod+2/3/4 (diff/terminal/git) and switch_tab_1..9 bindings
so numbered surface switching goes only through the new mechanism.
- Replace the help-dialog 'Switch Project' row with the surface-switch row and
update the shortcuts footer/header icons to the command icon.