Replace bar-settings with unified settings plugin

Consolidates bar-settings into a single 'settings' plugin with sidebar
categories: Defaults, Style, Bar, System, Plugins. Updates supporting
commands (omarchy-launch-settings, omarchy-style-corners-quickshell,
omarchy-theme-list-with-previews, omarchy-hyprland-monitor-scaling-set)
and refreshes sidebar glyphs to Nerd Font icons.

default/hypr/autostart.lua

@@ -1,7 +1,7 @@
 hl.on("hyprland.start", function()
   hl.exec_cmd("uwsm-app -- hypridle")
   hl.exec_cmd("uwsm-app -- mako")
-  hl.exec_cmd("! omarchy-toggle-enabled bar-off && omarchy-restart-quickshell")
+  hl.exec_cmd("omarchy-restart-quickshell")
   hl.exec_cmd("uwsm-app -- fcitx5 --disable notificationitem")
   hl.exec_cmd("uwsm-app -- swaybg -i ~/.config/omarchy/current/background -m fill")
   hl.exec_cmd("/usr/lib/polkit-gnome/polkit-gnome-authentication-agent-1")