Switch lockscreen from swaylock to gtklock. CSS styled with Star Wars
yellow (#FFE81F) on near-black background, cover-scaled wallpaper injected
at runtime via temp CSS to avoid path expansion issues in gtklock config.
Update sway background wallpaper to darth-vader-sam.jpg.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
