Waybar's include directive cannot merge arrays, making per-machine
module customization impossible without duplicating the entire config.
moonarch-waybar merges an optional ~/.config/waybar/userconfig with
the system config, supporting prepend/append on module arrays and
object merge for module definitions. Generates user style.css with
@import of system styles on first run.
System waybar config converted from JSONC to valid JSON for jq
compatibility. Niri startup and hotkey updated to use the wrapper.
