skel: purge KDE/Breeze leftovers, add proper GNOME light blue Antergos theme

- Removed KDE/Breeze gtkrc, gtkrc-2.0, .gtkrc-2.0, colors.css,
  window_decorations.css, SVG assets, antergos-log-tool.desktop
- Fixed .bashrc: dropped exo-open fallback (XFCE)
- Fixed firefox.desktop: removed dead antergos.com URL
- Fixed user-commands: calamares -> cnchi
- Fixed PKGBUILD maintainer email
- Fixed wallpaper gschema override path
- Added proper light blue (#1d90cd) GTK3/GTK4 user CSS
- Added Antergos-NeXT GNOME Shell theme with dark panel
- Wired shell theme via gsettings + dbus-launch in chroot
- Added out/ and work/ to .gitignore

airootfs/usr/share/themes/Antergos-NeXT/index.theme

@@ -0,0 +1,12 @@
+[Desktop Entry]
+Type=X-GNOME-Metatheme
+Name=Antergos-NeXT
+Comment=Antergos NeXT light theme with blue accents
+Encoding=UTF-8
+
+[X-GNOME-Metatheme]
+GtkTheme=Antergos-NeXT
+MetacityTheme=Antergos-NeXT
+IconTheme=Adwaita
+CursorTheme=Adwaita
+ButtonLayout=: