Add E2E tests for internationalization across multiple pages

- Implemented navigation.spec.ts to test language switching and translation of navigation elements.
- Created sessions-page.spec.ts to verify translations on the sessions page, including headers, status badges, and date formatting.
- Developed settings-page.spec.ts to ensure settings page content is translated and persists across sessions.
- Added skills-page.spec.ts to validate translations for skill categories, action buttons, and empty states.

ccw/frontend/vite.config.ts

@@ -1,6 +1,11 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 import path from 'path'
+import { fileURLToPath } from 'url'
+
+// ES module equivalent of __dirname
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
 
 // https://vite.dev/config/
 export default defineConfig({
@@ -9,6 +14,7 @@ export default defineConfig({
     alias: {
       '@': path.resolve(__dirname, './src'),
     },
+    extensions: ['.ts', '.tsx', '.js', '.jsx', '.json'],
   },
   server: {
     port: 5173,
@@ -27,4 +33,23 @@ export default defineConfig({
     outDir: 'dist',
     sourcemap: true,
   },
+  test: {
+    globals: true,
+    environment: 'jsdom',
+    setupFiles: './src/test/setup.ts',
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+      exclude: [
+        'node_modules/',
+        'src/test/',
+        '**/*.d.ts',
+        '**/*.config.*',
+        '**/mockData/*',
+        'src/main.tsx',
+      ],
+    },
+    include: ['src/**/*.{test,spec}.{ts,tsx}'],
+    css: true,
+  },
 })