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/bluetooth/Panel.qml

@@ -603,14 +603,14 @@ Panel {
     id: phraseSwap
     PropertyAnimation {
       target: heroStatus; property: "opacity"
-      to: 0.0; duration: 180; easing.type: Easing.OutQuad
+      to: 0.0; duration: Style.duration(180); easing.type: Easing.OutQuad
     }
     ScriptAction {
       script: root.phraseIndex = (root.phraseIndex + 1) % root.activePhrases.length
     }
     PropertyAnimation {
       target: heroStatus; property: "opacity"
-      to: 1.0; duration: 260; easing.type: Easing.InQuad
+      to: 1.0; duration: Style.duration(260); easing.type: Easing.InQuad
     }
   }