Reduced motion starts the view still instead of locking animation off

With Windows "Animation effects" off, browsers report prefers-reduced-motion, and the viewer
turned every animation off and hid the animation button, so presses, belts and robot arms
stood still in Brave and Firefox with no way to start them. Now that preference only picks
the starting mode ("off"); the button stays (its tooltip says why it is off) and the
viewer's choice wins and is remembered. The CSS still-picture rules apply only until the
viewer turns animation on (.iso-anim-on).

Also: switching light -> off -> smooth redraws the scene so the animations paused by script
run again (they ignore CSS play states).

Checks: web 93/93 (reduced motion: starts still, one click runs it, kept after reload),
Studio 109/109, 70 Rust tests. Tried in real Brave (system setting) and Firefox.

README.md

@@ -206,6 +206,8 @@ default ("light"): running CSS animations repaint the whole drawing every frame,
 which keeps a slow laptop busy. The ▷ button in the view toolbar switches
 between light, smooth and off, and the browser remembers the choice. In
 `isokit.toml`, `[build] animation = "smooth"` sets the default for built pages.
+When the system asks for less motion (Windows: Settings → Accessibility →
+Visual effects → Animation effects off), views start still; ▷ turns them on.
 
 ## Commands