feat: add keyboard navigation, escape-to-close modals, skip-to-content (A11Y-02)

All modals now close with Escape key. Interactive card divs respond to
Enter key. Skip-to-content link added to Dashboard layout. All Web5 and
Settings modals get role=dialog, aria-modal, and escape handlers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

neode-ui/src/views/Apps.vue

@@ -46,9 +46,11 @@
         data-controller-container
         :data-controller-launch="canLaunch(pkg) ? '' : undefined"
         tabindex="0"
+        role="link"
         class="glass-card card-stagger p-6 transition-all hover:-translate-y-1 cursor-pointer relative min-w-0 overflow-hidden"
         :style="{ '--stagger-index': index }"
         @click="goToApp(id as string)"
+        @keydown.enter="goToApp(id as string)"
       >
         <!-- Uninstall Icon -->
         <button