Move Fluidd/Tampermonkey links to settings modal; remove footer tip

- Tip text about printer_url removed from the footer
- Fluidd bookmarklet and Tampermonkey userscript buttons moved into
  the settings modal under a "Fluidd integration" section
- Footer is now empty and hidden

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>