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/DaylightStrip.qml

@@ -115,7 +115,7 @@ Item {
         color: strip.foreground
       }
 
-      Behavior on x { NumberAnimation { duration: 400; easing.type: Easing.OutCubic } }
+      Behavior on x { NumberAnimation { duration: Style.duration(400); easing.type: Easing.OutCubic } }
     }
   }
 
@@ -182,7 +182,7 @@ Item {
       // Gone rather than faded, so a hidden arrow is also untappable.
       opacity: strip.hovered && !arrow.covered ? 1 : 0
       visible: opacity > 0
-      Behavior on opacity { NumberAnimation { duration: 160 } }
+      Behavior on opacity { NumberAnimation { duration: Style.duration(160) } }
 
       // Sunrise sits a little high and sunset a little low: a cue that needs no reading.
       transform: Translate { y: arrow.rising ? -Style.space(2) : Style.space(2) }