feat(frontend): scaffold PWA with LiveKit join flow

Vite + React + TS + Tailwind v4, installable PWA. Join-pod UI that fetches a
LiveKit token from the backend, connects to the pod room, and publishes screen
+ mic so PodMan can watch.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/vite.config.ts

@@ -0,0 +1,25 @@
+import { defineConfig } from 'vite';
+import react from '@vitejs/plugin-react';
+import tailwindcss from '@tailwindcss/vite';
+import { VitePWA } from 'vite-plugin-pwa';
+
+export default defineConfig({
+  plugins: [
+    react(),
+    tailwindcss(),
+    VitePWA({
+      registerType: 'autoUpdate',
+      manifest: {
+        name: 'PodMan',
+        short_name: 'PodMan',
+        description: 'Ambient AI teammate that prevents merge collisions before push',
+        theme_color: '#0b0f17',
+        background_color: '#0b0f17',
+        display: 'standalone',
+      },
+    }),
+  ],
+  server: {
+    port: 5173,
+  },
+});