Fix bos-settings compile errors and use REGISTRY_TOKEN for publishing

bos-settings was scaffolded but never compiled. Fixes:
- main.rs: import gtk4::prelude (connect_activate/run)
- window.rs: disambiguate WidgetExt::display(); drop unused GBox import
- hyprland.rs: Label has no set_monospace -> use the monospace CSS class
- theme.rs: drop unused prelude import

Also switch package.yml to secrets.REGISTRY_TOKEN (scoped write:package),
since the auto Actions token is not authorized for the owner registry.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.forgejo/workflows/package.yml

@@ -14,7 +14,7 @@ jobs:
       # actions require. Everything runs as shell steps and clones manually.
       - name: Build and publish
         env:
-          PUBLISH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          PUBLISH_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
         run: |
           set -euo pipefail
           VERSION="${GITHUB_REF_NAME#v}"