feat: frontend remote relay, kiosk hardening, CSS compositor fix

Frontend:
- Add remote-relay.ts: receives companion input via /ws/remote-relay,
  dispatches keyboard/mouse/scroll events into browser DOM
- Add CompanionIndicator.vue: NES gamepad icon when companion connected
- Wire relay start/stop to auth state in App.vue

Kiosk:
- Move Chromium data dir to /var/lib/archipelago/chromium-kiosk (encrypted)
- Disable MetricsReporting, AutofillServerCommunication, PasswordManager
- Remove --metrics-recording-only (contradicts disable-metrics)

CSS:
- Fix Chromium ghost rectangles: only apply preserve-3d + backface-visibility
  during transitions, not always-on (causes Chromium to skip painting
  off-viewport cards)

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

neode-ui/src/App.vue

@@ -37,6 +37,9 @@
     <!-- PWA Install Prompt (Install app, not just Add to Home Screen) -->
     <PWAInstallPrompt />
 
+    <!-- Companion app connected indicator -->
+    <CompanionIndicator />
+
     <!-- Toast notifications - top right, glass style, any page -->
     <Teleport to="body">
       <Transition name="toast">
@@ -75,6 +78,7 @@ import AppLauncherOverlay from './components/AppLauncherOverlay.vue'
 import ToastStack from './components/ToastStack.vue'
 import Screensaver from './components/Screensaver.vue'
 import HelpGuideModal from './components/HelpGuideModal.vue'
+import CompanionIndicator from './components/CompanionIndicator.vue'
 import { useControllerNav } from '@/composables/useControllerNav'
 import { playKeyboardTypingSound } from '@/composables/useLoginSounds'
 import { useSpotlightStore } from '@/stores/spotlight'
@@ -83,6 +87,7 @@ import { useMessageToast } from '@/composables/useMessageToast'
 import { useAppStore } from '@/stores/app'
 import { useScreensaverStore } from '@/stores/screensaver'
 import { useUIModeStore } from '@/stores/uiMode'
+import { startRemoteRelay, stopRemoteRelay } from '@/api/remote-relay'
 
 const router = useRouter()
 const screensaverStore = useScreensaverStore()
@@ -95,16 +100,18 @@ const toastMessage = messageToast.toastMessage
 
 useControllerNav()
 
-// Start/stop message polling when auth state changes
+// Start/stop message polling and remote relay when auth state changes
 watch(() => appStore.isAuthenticated, (authenticated) => {
   if (authenticated) {
     messageToast.startPolling()
     screensaverStore.resetInactivityTimer()
+    startRemoteRelay()
   } else {
     messageToast.stopPolling()
     toastMessage.value = { show: false, text: '' }
     screensaverStore.clearInactivityTimer()
     screensaverStore.deactivate()
+    stopRemoteRelay()
   }
 }, { immediate: true })