feat(tags): enable web page viewing for note items containing URLs
Notes (text items) that contain URLs now get the same web page viewing
treatment as URL-type items. Changes:
- Add extractUrl() utility to detect URLs in text content (full URLs,
bare domains, and URLs embedded in text)
- Add openItemUrl() that routes through api.window.open() -> peek://page
webview container, same path as URL items
- Cards for notes with URLs show a link icon and the URL as subtitle
- Cards with URLs (both URL items and notes) get an 'Open Page' button
- Edit modal shows an 'Open Page' button for any item with a URL
- Groups extension also opens notes-with-URLs alongside URL items