feat(ui): redesign the default shortcut layout around a mod+k leader

Single chords stay for everyday actions; open/go actions move to two-step
mod+k sequences; held mod+digit switches header session tabs and held
mod+alt+digit switches context panel surfaces. Rare actions leave the
shortcut schema for the command palette, every remaining action ships with
a default binding, and stored overrides from the old layout reset once.
Key matching now follows the physical key on non-Latin layouts and for
Option-modified digits on macOS, including in the recording dialog.

packages/ui/src/lib/shortcuts/index.ts

@@ -8,6 +8,8 @@ export {
   keyToShortcutToken,
   normalizeCombo,
   parseShortcut,
+  resolveShortcutEventDigit,
+  resolveShortcutEventKey,
   UNASSIGNED_SHORTCUT,
 } from './bindings';
 export type { ShortcutCombo } from './bindings';