Extract bos-settings into its own repo; add Appearance/Startup Apps/Display editors

Split out of the bos repo so a bos-settings release no longer requires a
BOS ISO release (and vice versa) — CI here publishes straight to the
[breadway] pacman repo on tag push, independent of bos's own release cadence.

Also adds real GUI editors for the Hyprland JSON config surfaces bos gained
recently (hypr/settings.json, hypr/monitors.json, hypr/autostart.json):
- Appearance panel: gaps, borders (with a real color picker), blur, shadow,
  tiling layout, and basic input settings.
- Display panel: a monitor-rule list editor alongside the existing live
  connected-monitor readout.
- Startup Apps panel: toggle/edit/add/remove the extra autostart commands.
- --page argv support for deep-linking (breadhelp's guides can now open
  bos-settings straight to a specific page).
- Fixed a stale "View keybinds cheat sheet" button pointing at a file
  deleted when breadhelp replaced bos-keybinds/bos-welcome.

README.md

@@ -0,0 +1,15 @@
+# bos-settings
+
+System settings app for [BOS (Bread Operating System)](https://github.com/Breadway/bos) — GTK4, configures every bread\* app's config plus core system settings (network, sound, power, users, firewall, snapshots, packages, AUR, firmware, Hyprland display/appearance/autostart) non-destructively.
+
+Split out of the `bos` repo into its own repo so a bos-settings release doesn't require a BOS ISO release, and vice versa. Still the only pacman-packaged (not bakery-managed) bread app — see `packaging/README.md`.
+
+## Building
+
+```bash
+cargo build --release
+```
+
+## Packaging / releasing
+
+See `packaging/README.md`. In short: bump `Cargo.toml`'s version, tag `vX.Y.Z`, push the tag to both remotes — `.forgejo/workflows/package.yml` builds and publishes to the `[breadway]` pacman repo automatically.