test(renderer): add failing test for cn() helper + vitest config

vitest.config.ts

@@ -0,0 +1,23 @@
+import { defineConfig } from 'vitest/config';
+import react from '@vitejs/plugin-react';
+import path from 'path';
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    environment: 'jsdom',
+    globals: true,
+    setupFiles: ['./src/renderer/test/setup.ts'],
+    include: ['tests/**/*.{test,spec}.{ts,tsx}'],
+    coverage: {
+      provider: 'v8',
+      include: ['src/renderer/**/*.{ts,tsx}'],
+      exclude: ['src/renderer/test/**', 'src/renderer/**/*.test.*'],
+    },
+  },
+  resolve: {
+    alias: {
+      '@': path.join(__dirname, 'src/renderer'),
+    },
+  },
+});