Support Command Palette on iPad with hardware keyboard

[jkmassel]

Summary

@wordpress/commands ships a self-contained CommandMenu component that provides a Cmd+K command palette — but GutenbergKit never mounts it. On iPads with hardware keyboards, this means users have no access to the command palette at all.

Context

The package is already a direct dependency (used as a global in wordpress-globals.js), and as of @wordpress/commands 1.43.0 (#450) the palette now includes "Recently Used" command tracking. None of this is reachable today.

What's needed

1. Render <CommandMenu /> in the component tree (e.g. in src/components/layout/index.jsx) — this is the minimal change to make Cmd+K work.
2. Register commands — the palette will be empty unless commands are registered via useCommand() / useCommandLoader(). Need to determine which commands make sense in the native app context (e.g. block insertion, navigation, settings toggles).
3. Verify style loading — confirm that @wordpress/commands/build-style/style.css is bundled correctly.
4. Verify preferences persistence — the "recently used" feature writes to @wordpress/preferences. Need to confirm the persistence layer is wired up so recents survive across sessions.

Scope

This is only relevant for iPad with a hardware keyboard — there's no practical way to trigger Cmd+K on phones or tablets without a keyboard attached.