Printwright 1.1.1: light and dark theme

New

• Theme button in the top bar: ◐ auto (follows the system setting), ☀ light or ☾ dark. The browser keeps the choice, and the page does not flash light on load.

Fixes

• The parts header keeps Import…, Plate… and ↻ on one line. On screens below 1100 px, the "Parts" title hides to make room.

Docs

• The README demo GIF shows the light and the dark theme at once.

To update: pull, then restart the web app (systemctl --user restart printwright).

Full list: CHANGELOG.md