Chrome extension (Manifest V3) starter

Build a Chrome extension using Manifest V3 that [WHAT IT DOES ON A PAGE].

- manifest.json with the minimum permissions needed (explain each one); prefer activeTab over broad host permissions.
- A popup (HTML/CSS/JS) with the main controls.
- A content script that reads/modifies the page, and a background service worker for anything long-lived.
- Message passing between popup, content script, and service worker.
- Settings saved with chrome.storage.sync.
- No remote code; everything bundled in the extension.
Include steps to load it unpacked at chrome://extensions and how to package it for the Chrome Web Store.