feat(app): app icon and macOS bundle config

The dock showed a black square because tauri.conf.json had no bundle.icon
block and icons/ held only tiny placeholders with no .icns. Add an SVG
source logo (terminal prompt + split workspace panes), generate the full
icon set via `tauri icon` (icon.icns/.ico + all PNG/iOS/Android sizes), and
wire bundle.icon so the daemon embeds and macOS renders it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src-tauri/icons/android/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+  <foreground android:drawable="@mipmap/ic_launcher_foreground"/>
+  <background android:drawable="@color/ic_launcher_background"/>
+</adaptive-icon>

app/src-tauri/icons/android/values/ic_launcher_background.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <color name="ic_launcher_background">#fff</color>
+</resources>

app/src-tauri/icons/icon.svg

@@ -0,0 +1,32 @@
+<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="#222B3D"/>
+      <stop offset="1" stop-color="#0E131C"/>
+    </linearGradient>
+  </defs>
+
+  <!-- app tile -->
+  <rect x="84" y="84" width="856" height="856" rx="196" fill="url(#bg)"/>
+  <rect x="84" y="84" width="856" height="856" rx="196" fill="none" stroke="#3A4459" stroke-width="3"/>
+
+  <!-- workspace window -->
+  <rect x="214" y="270" width="596" height="452" rx="40" fill="#0B0F17" stroke="#33405A" stroke-width="4"/>
+  <!-- vertical split -->
+  <line x1="512" y1="318" x2="512" y2="674" stroke="#33405A" stroke-width="4"/>
+  <!-- focused left pane glow + accent edge -->
+  <rect x="214" y="270" width="298" height="452" rx="40" fill="#4F9CF9" opacity="0.12"/>
+  <path d="M226 312 q0 -30 30 -30 h214 q30 0 30 30 v368 q0 30 -30 30 h-214 q-30 0 -30 -30 Z" fill="none" stroke="#4F9CF9" stroke-width="8"/>
+
+  <!-- prompt chevron (filled) + cursor (left pane) -->
+  <path d="M282 426 L300 408 L364 472 q8 8 0 16 L300 552 L282 534 L338 480 Z" fill="#34D3C2"/>
+  <rect x="388" y="454" width="92" height="54" rx="11" fill="#34D3C2"/>
+
+  <!-- right pane: log lines -->
+  <g fill="#46546E">
+    <rect x="556" y="384" width="196" height="28" rx="14"/>
+    <rect x="556" y="450" width="150" height="28" rx="14"/>
+    <rect x="556" y="516" width="178" height="28" rx="14"/>
+    <rect x="556" y="582" width="120" height="28" rx="14"/>
+  </g>
+</svg>