Add fix-gtk4-dark.sh: repoint gtk.css symlink so GTK4/libadwaita apps go dark

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

fix-gtk4-dark.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# fix-gtk4-dark.sh — point ~/.config/gtk-4.0/gtk.css at the dark Breeze
+# GTK4 stylesheet so GTK4/libadwaita apps follow the dark desktop theme.
+#
+# Background: KDE's GTK sync (kde-gtk-config) symlinks gtk.css to the
+# LIGHT Breeze stylesheet. GTK loads that file at user priority, which
+# overrides libadwaita's dark mode, so GTK4 apps render light no matter
+# what. KDE may rewrite the symlink whenever "Apply" is hit on the
+# GNOME/GTK Application Style settings page — re-run this script if
+# GTK4 apps go light again. Restart affected apps to pick up the change.
+
+set -euo pipefail
+
+dark=/usr/share/themes/Breeze/gtk-4.0/gtk-dark.css
+target="$HOME/.config/gtk-4.0/gtk.css"
+
+if [ ! -f "$dark" ]; then
+    echo "error: $dark not found (is breeze-gtk installed?)" >&2
+    exit 1
+fi
+
+if [ "$(readlink -f "$target" 2>/dev/null)" = "$dark" ]; then
+    echo "already fixed: $target -> $dark"
+    exit 0
+fi
+
+mkdir -p "${target%/*}"
+ln -sfn "$dark" "$target"
+echo "fixed: $target -> $dark"
+echo "restart GTK4 apps to pick up the dark stylesheet"