test(web): setup frontend test infrastructure (#60)

- Add testing dependencies (vitest, vue-test-utils, testing-library, jsdom, msw)
- Create vitest.config.ts with jsdom environment and coverage settings
- Create setup.ts with Pinia initialization and fake timers
- Add test scripts to package.json (test, test:run, test:coverage)

Closes #56, closes #57

web/package.json

@@ -6,13 +6,22 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test": "vitest",
+    "test:run": "vitest run",
+    "test:coverage": "vitest run --coverage"
   },
   "devDependencies": {
+    "@testing-library/vue": "^8.1.0",
     "@vitejs/plugin-vue": "^5.2.4",
+    "@vitest/coverage-v8": "^2.1.8",
+    "@vue/test-utils": "^2.4.6",
+    "jsdom": "^25.0.1",
+    "msw": "^2.7.0",
     "sass": "^1.94.1",
     "typescript": "~5.9.3",
-    "vite": "^5.4.21"
+    "vite": "^5.4.21",
+    "vitest": "^2.1.8"
   },
   "dependencies": {
     "@vueuse/core": "^14.0.0",

web/src/__tests__/setup.ts

@@ -0,0 +1,15 @@
+import { vi, beforeEach, afterEach, beforeAll, afterAll } from 'vitest'
+import { createPinia, setActivePinia } from 'pinia'
+
+// Use fake timers globally for consistent async testing.
+vi.useFakeTimers()
+
+// Setup fresh Pinia instance for each test.
+beforeEach(() => {
+  setActivePinia(createPinia())
+})
+
+// Cleanup after each test.
+afterEach(() => {
+  vi.clearAllMocks()
+})

web/vitest.config.ts

@@ -0,0 +1,27 @@
+import { defineConfig } from 'vitest/config'
+import vue from '@vitejs/plugin-vue'
+import { resolve } from 'path'
+
+export default defineConfig({
+  plugins: [vue()],
+  test: {
+    environment: 'jsdom',
+    globals: true,
+    setupFiles: ['./src/__tests__/setup.ts'],
+    include: ['src/**/*.test.ts'],
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+      exclude: [
+        'node_modules/',
+        'src/__tests__/',
+        '**/*.d.ts',
+      ],
+    },
+  },
+  resolve: {
+    alias: {
+      '@': resolve(__dirname, 'src'),
+    },
+  },
+})