feat: complete testing-tool browser extension with timestamp converter and storage cleaner

entrypoints/content.ts

@@ -0,0 +1,9 @@
+import '../.wxt/types/imports.d.ts';
+
+export default defineContentScript({
+  matches: ['<all_urls>'],
+  runAt: 'document_start',
+  main() {
+    // Content script placeholder
+  },
+});