Initialize frontend.

frontend/vitest.config.ts

@@ -0,0 +1,39 @@
+import { defineConfig } from 'vitest/config'
+import react from '@vitejs/plugin-react'
+import tsconfigPaths from 'vite-tsconfig-paths'
+
+export default defineConfig({
+  plugins: [react(), tsconfigPaths()],
+  test: {
+    environment: 'jsdom',
+    setupFiles: ['./test-setup.ts'],
+    globals: true,
+    css: true,
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+      exclude: [
+        'node_modules/',
+        'test-setup.ts',
+        '**/*.d.ts',
+        'build/',
+        '.react-router/',
+      ],
+      thresholds: {
+        global: {
+          branches: 80,
+          functions: 80,
+          lines: 80,
+          statements: 80,
+        },
+      },
+    },
+    include: ['app/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
+    exclude: [
+      'node_modules/',
+      'build/',
+      '.react-router/',
+      'public/',
+    ],
+  },
+})