chore(ui): add Vitest + Testing Library scaffolding

Prepares for Plan 03 unit tests (MustacheEditor, NotificationBell, wizard step
validation). jsdom environment + jest-dom matchers + canary test verifies the
wiring.

ui/package.json

@@ -12,6 +12,9 @@
     "preview": "vite preview",
     "generate-api": "openapi-typescript src/api/openapi.json -o src/api/schema.d.ts",
     "generate-api:live": "curl -s http://192.168.50.86:30090/api/v1/api-docs -o src/api/openapi.json && openapi-typescript src/api/openapi.json -o src/api/schema.d.ts",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:ui": "vitest --ui",
     "postinstall": "node -e \"const fs=require('fs');fs.mkdirSync('public',{recursive:true});fs.copyFileSync('node_modules/@cameleer/design-system/assets/cameleer-logo.svg','public/favicon.svg')\""
   },
   "dependencies": {
@@ -30,19 +33,25 @@
   "devDependencies": {
     "@eslint/js": "^9.39.4",
     "@playwright/test": "^1.58.2",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@testing-library/user-event": "^14.6.1",
     "@types/js-yaml": "^4.0.9",
     "@types/node": "^24.12.0",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^6.0.0",
+    "@vitest/ui": "^4.1.4",
     "cross-env": "^10.1.0",
     "eslint": "^9.39.4",
     "eslint-plugin-react-hooks": "^7.0.1",
     "eslint-plugin-react-refresh": "^0.5.2",
     "globals": "^17.4.0",
+    "jsdom": "^29.0.2",
     "openapi-typescript": "^7.13.0",
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.56.1",
-    "vite": "^8.0.0"
+    "vite": "^8.0.0",
+    "vitest": "^4.1.4"
   }
 }

ui/src/test/canary.test.ts

@@ -0,0 +1,7 @@
+import { describe, it, expect } from 'vitest';
+
+describe('vitest canary', () => {
+  it('arithmetic still works', () => {
+    expect(1 + 1).toBe(2);
+  });
+});

ui/src/test/setup.ts

@@ -0,0 +1,7 @@
+import '@testing-library/jest-dom/vitest';
+import { cleanup } from '@testing-library/react';
+import { afterEach } from 'vitest';
+
+afterEach(() => {
+  cleanup();
+});

ui/vitest.config.ts

@@ -0,0 +1,14 @@
+import { defineConfig } from 'vitest/config';
+import react from '@vitejs/plugin-react';
+
+export default defineConfig({
+  plugins: [react()],
+  test: {
+    environment: 'jsdom',
+    globals: true,
+    setupFiles: ['./src/test/setup.ts'],
+    include: ['src/**/*.test.{ts,tsx}'],
+    exclude: ['src/test/e2e/**', 'node_modules/**'],
+    css: true,
+  },
+});