feat(icons): Orbit app icon + template tray icon across all clients

New brand icon (Orbit — a node circling a block-cursor core, amber-gold on
warm-dark, matching the desktop theme):
- iOS: Assets.xcassets/AppIcon.appiconset (opaque 1024, was no icon)
- desktop: resources/icon.png (rounded 1024 → .icns at package time)
- desktop tray: trayTemplate.png/@2x — a proper macOS TEMPLATE (black shapes on
  transparent, system-tinted) replacing the old white blob
- web: public/icon.svg (vector favicon/PWA)
Master SVGs rendered with rsvg-convert.

public/icon.svg

@@ -1,17 +1,43 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512" width="512" height="512">
+<svg width="1024" height="1024" viewBox="0 0 1024 1024" xmlns="http://www.w3.org/2000/svg">
   <defs>
-    <linearGradient id="bg" x1="0" y1="0" x2="1" y2="1">
-      <stop offset="0" stop-color="#1a1c26"/>
-      <stop offset="1" stop-color="#0e0f13"/>
+    <radialGradient id="bg" cx="32%" cy="25%" r="95%">
+      <stop offset="0" stop-color="#2b2016"/>
+      <stop offset="70%" stop-color="#13100c"/>
+      <stop offset="100%" stop-color="#0b0a08"/>
+    </radialGradient>
+    <linearGradient id="ring" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0" stop-color="#f2bd62"/>
+      <stop offset="1" stop-color="#c4842b"/>
     </linearGradient>
-    <linearGradient id="fg" x1="0" y1="0" x2="1" y2="1">
-      <stop offset="0" stop-color="#9d7cff"/>
-      <stop offset="1" stop-color="#7c8cff"/>
+    <linearGradient id="core" x1="0.3" y1="0" x2="0.7" y2="1">
+      <stop offset="0" stop-color="#f4c168"/>
+      <stop offset="1" stop-color="#d99a3e"/>
     </linearGradient>
+    <radialGradient id="node" cx="38%" cy="34%" r="72%">
+      <stop offset="0" stop-color="#ffd688"/>
+      <stop offset="1" stop-color="#e3a64a"/>
+    </radialGradient>
+    <radialGradient id="glow" cx="50%" cy="50%" r="50%">
+      <stop offset="0" stop-color="#e3a64a" stop-opacity="0.42"/>
+      <stop offset="100%" stop-color="#e3a64a" stop-opacity="0"/>
+    </radialGradient>
   </defs>
-  <rect width="512" height="512" rx="112" fill="url(#bg)"/>
-  <g fill="none" stroke="url(#fg)" stroke-width="36" stroke-linecap="round" stroke-linejoin="round">
-    <polyline points="150,196 226,256 150,316"/>
-    <line x1="268" y1="320" x2="372" y2="320"/>
+
+  <!-- warm-dark rounded-square ground (transparent corners for macOS/web) -->
+  <rect x="0" y="0" width="1024" height="1024" rx="232" fill="url(#bg)"/>
+  <rect x="1" y="1" width="1022" height="1022" rx="231" fill="none" stroke="#ffffff" stroke-opacity="0.05" stroke-width="2"/>
+
+  <!-- warmth behind the core -->
+  <circle cx="512" cy="520" r="250" fill="url(#glow)"/>
+
+  <!-- orbit ring + node share one tilt so the node sits on the ring -->
+  <g transform="rotate(-20 512 520)">
+    <ellipse cx="512" cy="520" rx="330" ry="146" fill="none" stroke="url(#ring)" stroke-width="26" stroke-opacity="0.9"/>
+    <!-- node on the ring (upper-right), with a faint motion trail -->
+    <path d="M 610 407 A 330 146 0 0 1 772 431" fill="none" stroke="#e3a64a" stroke-width="18" stroke-linecap="round" stroke-opacity="0.28"/>
+    <circle cx="772" cy="431" r="60" fill="url(#node)"/>
   </g>
+
+  <!-- the constant: a gold block cursor at the core -->
+  <rect x="440" y="448" width="144" height="144" rx="30" fill="url(#core)"/>
 </svg>