feat: add afterPack icon patching script

scripts/afterPack.cjs

@@ -0,0 +1,32 @@
+const path = require("path");
+
+module.exports = async function afterPack(context) {
+  let rcedit;
+  try {
+    rcedit = require("rcedit").rcedit;
+  } catch {
+    console.warn("  rcedit: skipped - rcedit not installed");
+    return;
+  }
+
+  const productFilename = context.packager?.appInfo?.productFilename;
+  if (!productFilename) {
+    console.warn("  rcedit: skipped - productFilename not available");
+    return;
+  }
+
+  const exePath = path.join(context.appOutDir, `${productFilename}.exe`);
+  const iconPath = path.resolve(__dirname, "..", "assets", "app_icon.ico");
+
+  try {
+    const fs = require("fs");
+    if (!fs.existsSync(iconPath)) {
+      console.warn("  rcedit: skipped - app_icon.ico not found");
+      return;
+    }
+    console.log(`  rcedit: patching icon -> ${exePath}`);
+    await rcedit(exePath, { icon: iconPath });
+  } catch (error) {
+    console.warn(`  rcedit: failed - ${String(error)}`);
+  }
+};