Add a no-animations mode, on by default in VMs (#13550)

A machine without a GPU, like most VMs, renders through llvmpipe on the
CPU, where every animated frame and every translucent window costs. In a
VM, opening and closing a terminal took ~5s of CPU; a panel ~3.4s.

omarchy toggle animations (also under Toggle > Animations) places a Hyprland
flag that turns off animations, blur and shadows and makes windows opaque.
The shell follows Hyprland's animations:enabled, rereading it on every
config reload: its one-shot animations run for Style.duration(ms), which
is then 0, and its spinners, pulses and title marquee hold still. A new
install in a VM starts with the flag in place.

Measured in the ISO test VM (llvmpipe), CPU per interaction:
terminal open+close 5000ms -> 481ms, workspace switch 1670ms -> 409ms,
audio panel 3446ms -> 796ms, volume OSD 2324ms -> 584ms, menu 2028ms ->
1241ms.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

shell/plugins/panels/elsewhen/Panel.qml

@@ -631,7 +631,7 @@ Panel {
   // Heavy on the way out, brisk on the way back.
   Behavior on zoom {
     NumberAnimation {
-      duration: root.zoomDuration
+      duration: Style.duration(root.zoomDuration)
       easing.type: root.zoomEasing
     }
   }
@@ -649,14 +649,14 @@ Panel {
 
   Behavior on moonDemo {
     enabled: root.moonShowing
-    NumberAnimation { duration: 460; easing.type: Easing.InOutSine }
+    NumberAnimation { duration: Style.duration(460); easing.type: Easing.InOutSine }
   }
 
   NumberAnimation {
     id: dropAnimation
     target: root
     property: "dragOffset"
-    duration: 150
+    duration: Style.duration(150)
     easing.type: Easing.OutCubic
     onFinished: root.commitRowDrag()
   }
@@ -805,7 +805,7 @@ Panel {
           id: scrollAnim
           target: scroller
           property: "contentY"
-          duration: 160
+          duration: Style.duration(160)
           easing.type: Easing.OutCubic
         }