refactor: migrate from CRA to Vite and improve testing

Replace Create React App with Vite build system
Add ESLint configuration and improve TypeScript types
Create VSCode UI component mocks for better testing
Update test files with proper async handling
Add Tailwind CSS integration
Fix accessibility by adding ARIA roles

webview-ui/vite.config.mts

@@ -0,0 +1,23 @@
+import { defineConfig } from "vite";
+import react from "@vitejs/plugin-react";
+import tailwindcss from "@tailwindcss/vite";
+
+export default defineConfig({
+  plugins: [
+    react(),
+    tailwindcss(),
+  ],
+  build: {
+    outDir: "build",
+    rollupOptions: {
+      output: {
+        entryFileNames: `assets/[name].js`,
+        chunkFileNames: `assets/[name].js`,
+        assetFileNames: `assets/[name].[ext]`,
+      },
+    },
+  },
+  server: {
+    port: 3000,
+  },
+});