fix: correct default_locale to zh_CN to match _locales directory

package.json

@@ -2,7 +2,7 @@
   "name": "testing-tools",
   "description": "A browser extension providing useful testing tools including timestamp conversion and storage management",
   "private": false,
-  "version": "1.0.0",
+  "version": "1.0.6",
   "license": "MIT",
   "type": "module",
   "scripts": {

wxt.config.ts

@@ -45,7 +45,7 @@ export default defineConfig({
     name: 'Testing Tool',
     description: 'A tool for testing web applications.',
     version_name: undefined,
-    default_locale: 'zh',
+    default_locale: 'zh_CN',
     permissions: [
       'storage',
       'unlimitedStorage',