fix: Add babel configuration for Playwright to handle TypeScript declare fields

- Configure babel plugins for TypeScript with allowDeclareFields option
- Add module resolver for @ alias to src directory
- Create custom babel plugin to stub Vue/CSS imports
- Add browser globals polyfill using happy-dom for Node.js context
- Update playwright.i18n.config.ts with babel configuration

This enables collect-i18n tests to run with proper TypeScript and module transformations.

babel.config.json

@@ -0,0 +1,24 @@
+{
+  "presets": [
+    "@babel/preset-env",
+    [
+      "@babel/preset-typescript",
+      {
+        "allowDeclareFields": true,
+        "onlyRemoveTypeImports": true
+      }
+    ]
+  ],
+  "plugins": [
+    [
+      "babel-plugin-module-resolver",
+      {
+        "root": ["./"],
+        "alias": {
+          "@": "./src"
+        }
+      }
+    ],
+    "@vue/babel-plugin-jsx"
+  ]
+}