Reword code comments in plain technical language

Comments only, no code changes. Replaces vague or personified phrasing
with explicit statements of what the code does and why, uses bullet
lists for multi-case behavior, and fixes the settings path in
WindowSettings.h (~/.config/sloposk/sloposk.conf).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

qml/BarToggle.qml

@@ -1,7 +1,7 @@
 import QtQuick
 
-// A small on/off button in the grab bar; lit while on. The icon goes inside
-// and should draw in `foreground`.
+// On/off button in the grab bar, highlighted while on.
+// Child items form the icon and should use `foreground` as their color.
 Item {
     id: toggle