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.

bin/omarchy-launch-settings

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# omarchy:summary=Launch the Omarchy settings panel
+# omarchy:group=launch
+# omarchy:name=settings
+# omarchy:args=[bar|plugins|defaults|style]
+# omarchy:examples=omarchy launch settings | omarchy launch settings defaults | omarchy launch settings style
+
+category="${1:-}"
+payload="{}"
+case "$category" in
+  bar|plugins|defaults|style)
+    payload=$(printf '{"category":"%s"}' "$category")
+    ;;
+  "")
+    ;;
+  *)
+    echo "Usage: omarchy-launch-settings [bar|plugins|defaults|style]" >&2
+    exit 1
+    ;;
+esac
+
+exec omarchy-shell-ipc shell summon omarchy.settings "$payload"