Add Ping frontend

React 19 + TypeScript client built with Vite. Zustand for local state,
react-oidc-context for the login flow, a SignalR connection for chat and
presence events, and LiveKit's React components for voice/video calls.

frontend/vite.config.ts

@@ -0,0 +1,9 @@
+import react from '@vitejs/plugin-react'
+import { defineConfig } from 'vite'
+
+export default defineConfig({
+  plugins: [react()],
+  server: {
+    port: 3100,
+  },
+})