Add standalone Vite build for simple-react example

Replace custom build.ts dependency with standard Vite setup:
- package.json with Vite scripts (dev, build, preview)
- Use @modelcontextprotocol/ext-apps package imports
- Standard Vite project structure (index.html at root)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

examples/simple-react/vite.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from "vite";
+import react from "@vitejs/plugin-react";
+
+export default defineConfig({
+  plugins: [react()],
+  build: {
+    // Output single HTML file with inlined JS for easy distribution
+    rollupOptions: {
+      output: {
+        inlineDynamicImports: true,
+      },
+    },
+  },
+});