feat(ui): companion app banner in the App Store + APK download unblocked

The App Store gains a "Your Node. In Your Pocket." hero banner for the
mobile companion app, in the same format as the featured-app banner, with
the app running on a phone mockup rising out of the right edge. Install
(or clicking anywhere on it) opens the Remote Companion download/pairing
modal — now openable on demand via a shared trigger instead of only
auto-showing once.

Also fixes the companion APK download on PWA installs: /packages/ now
bypasses the service worker's SPA fallback, which was answering the
download click with index.html instead of the file.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

neode-ui/src/views/Discover.vue

@@ -150,6 +150,9 @@
         </div>
       </div>
 
+      <!-- Mobile companion app banner — opens the download/pairing modal -->
+      <CompanionBanner />
+
       <!-- Category Section Divider -->
       <div class="flex items-center gap-3 mb-5">
         <span class="discover-terminal-tag">all</span>
@@ -239,6 +242,7 @@ import { useContainersScanTimeout } from '@/composables/useContainersScanTimeout
 import { APP_STORE_SECTIONS } from './appStoreCategories'
 import DiscoverHero from './discover/DiscoverHero.vue'
 import FeaturedApps from './discover/FeaturedApps.vue'
+import CompanionBanner from './discover/CompanionBanner.vue'
 import AppGrid from './discover/AppGrid.vue'
 import InstallVersionModal from '@/components/InstallVersionModal.vue'
 import type { MarketplaceApp, FeaturedApp } from './discover/types'