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/Ui/SpeedTestOverlay.qml

@@ -61,7 +61,7 @@ PanelWindow {
   onRightValueChanged: expandScale(rightValue)
 
   Behavior on fullScale {
-    NumberAnimation { duration: 400; easing.type: Easing.OutCubic }
+    NumberAnimation { duration: Style.duration(400); easing.type: Easing.OutCubic }
   }
 
   // The scrim below is a fixed near-black regardless of theme, so text and
@@ -178,7 +178,7 @@ PanelWindow {
           onClicked: root.runAgainRequested()
 
           Behavior on opacity {
-            NumberAnimation { duration: 240; easing.type: Easing.OutCubic }
+            NumberAnimation { duration: Style.duration(240); easing.type: Easing.OutCubic }
           }
         }
 
@@ -236,13 +236,13 @@ PanelWindow {
     opacity: engaged ? 1 : 0.5
 
     Behavior on opacity {
-      NumberAnimation { duration: 240; easing.type: Easing.OutCubic }
+      NumberAnimation { duration: Style.duration(240); easing.type: Easing.OutCubic }
     }
 
     // Live readings land once a second; glide between them rather than snap.
     Behavior on shown {
       enabled: !ignition.running
-      NumberAnimation { duration: 600; easing.type: Easing.OutCubic }
+      NumberAnimation { duration: Style.duration(600); easing.type: Easing.OutCubic }
     }
 
     onValueChanged: {
@@ -257,8 +257,8 @@ PanelWindow {
     // the live figures take over.
     SequentialAnimation {
       id: ignition
-      NumberAnimation { target: dial; property: "shown"; to: dial.fullScale; duration: 550; easing.type: Easing.InOutCubic }
-      NumberAnimation { target: dial; property: "shown"; to: 0; duration: 650; easing.type: Easing.OutCubic }
+      NumberAnimation { target: dial; property: "shown"; to: dial.fullScale; duration: Style.duration(550); easing.type: Easing.InOutCubic }
+      NumberAnimation { target: dial; property: "shown"; to: 0; duration: Style.duration(650); easing.type: Easing.OutCubic }
       onFinished: dial.shown = dial.value
     }