feat: add Vitest and Playwright testing frameworks

Set up Vitest for unit/integration tests and Playwright for E2E tests; add configs, tests, and documentation

Co-authored-by: Moheeb Zara <[email protected]>

vitest.config.ts

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