fix: onboarding gamepad focus styles + sounds

- glass-button gets orange glow on focus-visible (was suppressed)
- Input fields get orange border on focus-visible
- Restore link made focusable (tabindex, role, keydown.enter)
- Gamepad nav sounds play via existing fallback handler

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

neode-ui/src/views/OnboardingIntro.vue

@@ -26,8 +26,11 @@
         </button>
 
         <a
+          tabindex="0"
+          role="button"
           class="text-white/50 hover:text-white/80 underline text-sm cursor-pointer mt-4 block text-center onb-cta"
           @click="showRestore = true"
+          @keydown.enter="showRestore = true"
         >
           Restore from backup
         </a>