Accessibility: keyboard navigation for listbox popups #29

Accessibility: keyboard navigation for listbox popups

LanguageSwitcher, PhoneInput (country menu) and NavBar (language menu) all render role="listbox" popups, but the only key handled is Escape. Users can only Tab through options, which doesn't match the WAI-ARIA listbox / combobox pattern.

Expected

• ArrowDown / ArrowUp move the active option (from the search input too); wrap or clamp
• Home / End jump to first/last
• Enter selects the active option; Escape closes and returns focus to the trigger
• Active option exposed via aria-activedescendant on the search input (with role="combobox" + aria-controls)
• Active option scrolled into view
• Opening with ArrowDown on the trigger
• Focus returns to the trigger after selection

Acceptance

• Shared hook (e.g. src/lib/use-listbox-navigation.ts) used by all three components
• Tests with @testing-library/user-event covering the keys above for each component