bar: power button open session

Make it actually useful (not really)

modules/bar/components/Power.qml

@@ -1,10 +1,27 @@
 import "root:/widgets"
 import "root:/services"
 import "root:/config"
+import Quickshell
 
 MaterialIcon {
     text: "power_settings_new"
     color: Colours.palette.m3error
     font.bold: true
     font.pointSize: Appearance.font.size.normal
+
+    StateLayer {
+        anchors.fill: undefined
+        anchors.centerIn: parent
+        anchors.horizontalCenterOffset: 1
+
+        implicitWidth: parent.implicitHeight + Appearance.padding.small * 2
+        implicitHeight: implicitWidth
+
+        radius: Appearance.rounding.full
+
+        function onClicked(): void {
+            const v = Visibilities.screens[QsWindow.window.screen];
+            v.session = !v.session;
+        }
+    }
 }