[Fix Accessibility] Add focus-visible styles to keyboard navigation (#1722)
## 📁 File Changes (5 files modified): - `nav-drawer.js` - Added focus-visible styles to mobile menu button - `search.js` - Added focus-visible styles to mobile search button - `table-of-contents.js` - Added focus-visible styles to mobile TOC summary button - `variant-select.js` - Added focus-visible styles to CLI version selector button - `code.js` - Updated outlineOffset from 2px to 1px for clipboard copy button ## 📋 Summary: This PR improves keyboard accessibility by adding consistent focus-visible outline styles to interactive buttons across mobile components, ensuring better visual feedback for keyboard navigation users. ### `Keyboard focus indicator is not visible on 'search' icon` <img width="702" height="635" alt="image" src="https://github.com/user-attachments/assets/cd462a2e-49e1-4f42-8355-c459f601c10a" /> ### `Keyboard focus indicator is not visible on the 'Select CLI Version' button` <img width="687" height="635" alt="image" src="https://github.com/user-attachments/assets/3435c1e1-f508-4031-bbb1-e6b70fb3b88b" /> ### `Keyboard focus indicator is not visible on 'Table of contents` <img width="687" height="635" alt="image" src="https://github.com/user-attachments/assets/dafabd03-fece-4245-8d2a-b6ef0c27c163" />