Add Windows ARM64 packaging support

scripts/generate-win-icon.mjs

@@ -0,0 +1,46 @@
+import fs from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const projectRoot = path.resolve(__dirname, "..");
+
+const sourcePngPath = path.join(projectRoot, "src-tauri", "icons", "128x128@2x.png");
+const targetIcoPath = path.join(projectRoot, "src-tauri", "icons", "icon.ico");
+
+const pngBytes = fs.readFileSync(sourcePngPath);
+
+if (pngBytes.length < 24 || pngBytes.toString("ascii", 1, 4) !== "PNG") {
+  throw new Error(`Expected a PNG file at ${sourcePngPath}`);
+}
+
+const width = pngBytes.readUInt32BE(16);
+const height = pngBytes.readUInt32BE(20);
+
+if (width !== 256 || height !== 256) {
+  throw new Error(`Expected a 256x256 PNG, received ${width}x${height}`);
+}
+
+const headerSize = 6;
+const directoryEntrySize = 16;
+const imageOffset = headerSize + directoryEntrySize;
+const icoBytes = Buffer.alloc(imageOffset + pngBytes.length);
+
+icoBytes.writeUInt16LE(0, 0);
+icoBytes.writeUInt16LE(1, 2);
+icoBytes.writeUInt16LE(1, 4);
+
+icoBytes.writeUInt8(0, 6);
+icoBytes.writeUInt8(0, 7);
+icoBytes.writeUInt8(0, 8);
+icoBytes.writeUInt8(0, 9);
+icoBytes.writeUInt16LE(1, 10);
+icoBytes.writeUInt16LE(32, 12);
+icoBytes.writeUInt32LE(pngBytes.length, 14);
+icoBytes.writeUInt32LE(imageOffset, 18);
+
+pngBytes.copy(icoBytes, imageOffset);
+
+fs.writeFileSync(targetIcoPath, icoBytes);
+console.log(`Generated ${path.relative(projectRoot, targetIcoPath)} from ${path.relative(projectRoot, sourcePngPath)}`);