Add app icon and enable Windows installer packaging

- Generate radiation-trefoil app icon (ISO proportions) via app-icon.svg
- Enable bundling with NSIS + MSI targets
- Use English productName so WiX/MSI builds succeed

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

src-tauri/app-icon.svg

@@ -0,0 +1,14 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="1024" height="1024" viewBox="0 0 1024 1024">
+  <defs>
+    <linearGradient id="bg" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0" stop-color="#1f2a44"/>
+      <stop offset="1" stop-color="#0b1220"/>
+    </linearGradient>
+  </defs>
+  <rect x="0" y="0" width="1024" height="1024" rx="200" ry="200" fill="url(#bg)"/>
+  <circle cx="512" cy="512" r="395" fill="none" stroke="#facc15" stroke-width="22" opacity="0.35"/>
+  <g fill="#facc15">
+    <circle cx="512" cy="512" r="70"/>
+    <path d="M 687.00 208.89 A 350 350 0 0 0 337.00 208.89 L 459.50 421.07 A 105 105 0 0 1 564.50 421.07 Z M 162.00 512.00 A 350 350 0 0 0 337.00 815.11 L 459.50 602.93 A 105 105 0 0 1 407.00 512.00 Z M 687.00 815.11 A 350 350 0 0 0 862.00 512.00 L 617.00 512.00 A 105 105 0 0 1 564.50 602.93 Z"/>
+  </g>
+</svg>

src-tauri/tauri.conf.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
-  "productName": "建筑材料放射性判定",
+  "productName": "Building Material Radioactivity",
   "version": "0.1.0",
   "identifier": "com.tcjs.ceramic-radioactivity",
   "build": {
@@ -24,8 +24,14 @@
     }
   },
   "bundle": {
-    "active": false,
-    "targets": "all",
-    "icon": []
+    "active": true,
+    "targets": ["nsis", "msi"],
+    "icon": [
+      "icons/32x32.png",
+      "icons/128x128.png",
+      "icons/128x128@2x.png",
+      "icons/icon.icns",
+      "icons/icon.ico"
+    ]
   }
 }