refactor(bar): modularize bar widgets and layout

ui/ExclusionZone.qml

@@ -0,0 +1,12 @@
+pragma ComponentBehavior: Bound
+
+import Quickshell
+import Quickshell.Wayland
+
+PanelWindow {
+  property string name
+
+  implicitWidth: 0
+  implicitHeight: 0
+  WlrLayershell.namespace: `quickshell:${name}ExclusionZone`
+}