Add app icon, feature graphic, and justfile

- Network nodes tech-style icon (dark theme, cyan accents)
- Feature graphic for Play Store (1024x500)
- PNG icons for all densities
- Justfile with build, release, icons, install tasks

assets/icon.svg

@@ -0,0 +1,85 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512">
+  <defs>
+    <linearGradient id="bg" x1="0%" y1="0%" x2="100%" y2="100%">
+      <stop offset="0%" style="stop-color:#0f172a"/>
+      <stop offset="100%" style="stop-color:#1e293b"/>
+    </linearGradient>
+  </defs>
+
+  <!-- Dark background -->
+  <rect width="512" height="512" rx="96" fill="url(#bg)"/>
+
+  <!-- Circuit traces -->
+  <g stroke="#0ea5e9" stroke-width="3" fill="none" opacity="0.4">
+    <path d="M 80 256 H 140"/>
+    <path d="M 372 256 H 432"/>
+    <path d="M 256 80 V 140"/>
+    <path d="M 256 372 V 432"/>
+    <path d="M 140 180 L 180 140"/>
+    <path d="M 332 140 L 372 180"/>
+    <path d="M 140 332 L 180 372"/>
+    <path d="M 332 372 L 372 332"/>
+  </g>
+
+  <!-- Main connection lines -->
+  <g stroke="#0ea5e9" stroke-width="4" fill="none">
+    <!-- Center to outer nodes -->
+    <line x1="256" y1="256" x2="160" y2="160"/>
+    <line x1="256" y1="256" x2="352" y2="160"/>
+    <line x1="256" y1="256" x2="160" y2="352"/>
+    <line x1="256" y1="256" x2="352" y2="352"/>
+    <!-- Horizontal and vertical -->
+    <line x1="256" y1="256" x2="140" y2="256"/>
+    <line x1="256" y1="256" x2="372" y2="256"/>
+    <line x1="256" y1="256" x2="256" y2="140"/>
+    <line x1="256" y1="256" x2="256" y2="372"/>
+  </g>
+
+  <!-- Data flow dots (animated feel) -->
+  <g fill="#22d3ee">
+    <circle cx="190" cy="190" r="4"/>
+    <circle cx="322" cy="190" r="4"/>
+    <circle cx="190" cy="322" r="4"/>
+    <circle cx="322" cy="322" r="4"/>
+    <circle cx="180" cy="256" r="3"/>
+    <circle cx="332" cy="256" r="3"/>
+    <circle cx="256" cy="180" r="3"/>
+    <circle cx="256" cy="332" r="3"/>
+  </g>
+
+  <!-- Outer nodes -->
+  <g fill="#0f172a" stroke="#0ea5e9" stroke-width="3">
+    <circle cx="160" cy="160" r="24"/>
+    <circle cx="352" cy="160" r="24"/>
+    <circle cx="160" cy="352" r="24"/>
+    <circle cx="352" cy="352" r="24"/>
+    <circle cx="140" cy="256" r="20"/>
+    <circle cx="372" cy="256" r="20"/>
+    <circle cx="256" cy="140" r="20"/>
+    <circle cx="256" cy="372" r="20"/>
+  </g>
+
+  <!-- Inner node fills -->
+  <g fill="#22d3ee">
+    <circle cx="160" cy="160" r="10"/>
+    <circle cx="352" cy="160" r="10"/>
+    <circle cx="160" cy="352" r="10"/>
+    <circle cx="352" cy="352" r="10"/>
+    <circle cx="140" cy="256" r="8"/>
+    <circle cx="372" cy="256" r="8"/>
+    <circle cx="256" cy="140" r="8"/>
+    <circle cx="256" cy="372" r="8"/>
+  </g>
+
+  <!-- Center hub (phone) -->
+  <circle cx="256" cy="256" r="56" fill="#0f172a" stroke="#0ea5e9" stroke-width="4"/>
+  <circle cx="256" cy="256" r="40" fill="#0ea5e9"/>
+
+  <!-- Signal bars in center -->
+  <g fill="#0f172a">
+    <rect x="236" y="268" width="8" height="16" rx="2"/>
+    <rect x="248" y="258" width="8" height="26" rx="2"/>
+    <rect x="260" y="248" width="8" height="36" rx="2"/>
+    <rect x="272" y="238" width="8" height="46" rx="2"/>
+  </g>
+</svg>