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.

public/dock/contact.svg

@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100">
+<defs>
+<linearGradient id="bg" x1="0" y1="0" x2="0" y2="1"><stop offset="0" stop-color="#454b57"/><stop offset="1" stop-color="#1c2027"/></linearGradient>
+<linearGradient id="gl" x1="0" y1="0" x2="0" y2="1">
+<stop offset="0" stop-color="#fff" stop-opacity="0.28"/><stop offset="0.5" stop-color="#fff" stop-opacity="0"/></linearGradient>
+</defs>
+<rect x="4" y="4" width="92" height="92" rx="26" fill="url(#bg)"/>
+<rect x="4" y="4" width="92" height="92" rx="26" fill="url(#gl)"/>
+<rect x="4.75" y="4.75" width="90.5" height="90.5" rx="25.25" fill="none" stroke="#fff" stroke-opacity="0.14" stroke-width="1.5"/>
+<g fill="none" stroke="#fff" stroke-width="6" stroke-linecap="round" stroke-linejoin="round">
+<rect x="27" y="35" width="46" height="30" rx="6"/><path d="M30 40 L50 54 L70 40"/></g>
+</svg>