perf: consolidate notif timeStr timers into one global tick; fix osd open-on-start

modules/Volume.qml

@@ -39,11 +39,16 @@ M.BarSection {
     }
 
     property bool _osdActive: false
+    property bool _ready: false
     readonly property bool _anyHover: root._hovered || hoverPanel.panelHovered
     readonly property bool _showPanel: _anyHover || _osdActive
 
-    onVolumeChanged: _flashPanel()
-    onMutedChanged: _flashPanel()
+    Component.onCompleted: _ready = true
+
+    onVolumeChanged: if (_ready)
+        _flashPanel()
+    onMutedChanged: if (_ready)
+        _flashPanel()
 
     function _flashPanel() {
         _osdActive = true;