IMPROVED - Use swappable image icons and move controls to a corner dock

- Dock icons are now real SVG files under public/dock/ (macOS squircle
  look, active variants), so they can be replaced with custom art later.
- Full-bleed icons (DockIcon padding 0), fixed logo src to stop the
  refresh flash.
- Remove the top menu bar entirely; relocate theme/language/sound (+admin)
  into a corner control dock that expands on click.

components/ui/dock.tsx

@@ -107,7 +107,7 @@ const DockIcon = ({
   ...props
 }: DockIconProps) => {
   const ref = useRef<HTMLDivElement>(null);
-  const padding = Math.max(2, size * 0.05);
+  const padding = 0;
   const defaultMouseX = useMotionValue(Infinity);
 
   const distanceCalc = useTransform(mouseX ?? defaultMouseX, (val: number) => {