Initial commit — TANINUX (camel): management app + distro packaging

- app: GTK System Settings (tsettings) + Software Hub (thub) + TUI
- distro/: camel.toml manifest + MANIFEST.md (Arch + [tanin] repo model)
- packaging/: taninux, tanin-desktop (niri metapackage), tanin-greet,
  tanin-libadwaita, tanin-setup
- docs/, data/, LICENSE (GPL-3.0-or-later)

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

data/applications/ch.gabrielevarano.Taninux.Settings.desktop

@@ -0,0 +1,10 @@
+[Desktop Entry]
+Type=Application
+Name=System Settings
+Comment=System, hardware and personalization settings
+Exec=tsettings
+Icon=preferences-system
+Terminal=false
+Categories=Settings;GTK;
+Keywords=settings;system;kernel;display;audio;network;bluetooth;power;
+StartupNotify=true