add prefers-reduced-motion support (#audit-P2)

The transform: scale(.96) animation on button press (and all other
transitions/animations) had no reduced-motion alternative. Added:
@media (prefers-reduced-motion: reduce) { *, *::before, *::after {
  animation-duration: 0s !important;
  animation-iteration-count: 1 !important;
  transition-duration: 0s !important;
}}

Covers btn, btn-icon, snap-slot, transport-btn, switch, file-drop,
loader, and CSS-in-JS elements (preset-chip-s, param-btn, etc.).

public/img/fx_analyzer.svg

@@ -1,14 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Generator: Adobe Illustrator 16.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
-<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
-<svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" width="48px"
-	 height="48px" viewBox="0 0 48 48" enable-background="new 0 0 48 48" xml:space="preserve">
-<g id="Layer_1" display="none">
-	<path display="inline" d="M47,41c0,3.313-2.687,6-6,6H7c-3.313,0-6-2.687-6-6V7c0-3.313,2.687-6,6-6h34c3.313,0,6,2.687,6,6V41z"/>
-	<line display="inline" fill="none" stroke="#FFFFFF" stroke-width="5" x1="23.5" y1="10" x2="23.5" y2="22"/>
-	<line display="inline" fill="none" stroke="#FFFFFF" stroke-width="5" x1="43" y1="13.546" x2="19.938" y2="53.489"/>
-	<line display="inline" fill="none" stroke="#FFFFFF" stroke-width="5" x1="5" y1="13.545" x2="11.904" y2="25.504"/>
-</g>
+<svg version="1.1" xmlns="http://www.w3.org/2000/svg" x="0px" y="0px" width="48px"
+	 height="48px" viewBox="0 0 48 48" fill="#F0EDE6">
 <g id="Combined">
 	<path d="M41,1H7C3.687,1,1,3.687,1,7v34c0,3.313,2.687,6,6,6h13.798l20.037-34.704l4.33,2.5L26.571,47H41c3.313,0,6-2.687,6-6V7
 		C47,3.687,44.313,1,41,1z M9.739,26.754L2.835,14.795l4.33-2.5l6.904,11.958L9.739,26.754z M26,22h-5V10h5V22z"/>