feat(osd): add volume osd popup window

modules/osd/VolumeCard.qml

@@ -0,0 +1,42 @@
+pragma ComponentBehavior: Bound
+
+import QtQuick
+import Quickshell
+import qs.config
+import qs.services
+import qs.ui
+
+BarButton {
+    id: root
+
+    readonly property real level: Math.max(0, Math.min(Audio.muted ? 0 : Audio.volume, 1))
+    readonly property url iconUrl: `${Quickshell.shellPath("assets")}/icons/speaker.svg`
+
+    hoverHighlight: false
+    pointerCursor: false
+    iconOnly: true
+    iconSource: root.iconUrl
+    icon.width: Theme.volume.iconSize
+    icon.height: Theme.volume.iconSize
+
+    implicitWidth: Theme.volume.width
+    implicitHeight: Theme.volume.height
+
+    Rectangle {
+        id: fill
+
+        anchors.left: parent.left
+        anchors.top: parent.top
+        anchors.bottom: parent.bottom
+        implicitWidth: parent.width * root.level
+        radius: Theme.radius
+        color: Audio.muted ? Theme.colors.error : Theme.colors.accent
+        opacity: 0.35
+
+        Behavior on width {
+            NumberAnimation {
+                duration: Theme.duration
+            }
+        }
+    }
+}