Bug fix: resolved an issue where browser compatibility data was not being sent correctly on Firefox, causing sync failures with the backend service.

Added manual profile entry: users can now enter their LinkedIn URL directly if auto-detection doesn't work. Added Sync Now button for on-demand data sync. Connect button now persists attempt state across popup sessions. Improved sync feedback with fade animation. Shortened disclosure text. UI polish: removed rounded corners to match browser chrome, fixed hover states on disabled buttons.