Add portable Windows desktop downloads and release uploads

desktop/prepare-icon.mjs

@@ -0,0 +1,34 @@
+import sharp from "sharp";
+import { mkdir, writeFile } from "node:fs/promises";
+import { fileURLToPath } from "node:url";
+const assets = new URL("./assets/", import.meta.url);
+await mkdir(assets, { recursive: true });
+const source = fileURLToPath(new URL("../app/icon.png", import.meta.url));
+await sharp(source)
+  .resize(512, 512, { kernel: "nearest" })
+  .png()
+  .toFile(fileURLToPath(new URL("icon.png", assets)));
+const sizes = [16, 24, 32, 48, 64, 128, 256];
+const images = await Promise.all(
+  sizes.map((size) =>
+    sharp(source).resize(size, size, { kernel: "nearest" }).png().toBuffer(),
+  ),
+);
+const header = Buffer.alloc(6 + 16 * sizes.length);
+header.writeUInt16LE(1, 2);
+header.writeUInt16LE(sizes.length, 4);
+let offset = header.length;
+sizes.forEach((size, index) => {
+  const entry = 6 + index * 16;
+  header[entry] = size === 256 ? 0 : size;
+  header[entry + 1] = header[entry];
+  header.writeUInt16LE(1, entry + 4);
+  header.writeUInt16LE(32, entry + 6);
+  header.writeUInt32LE(images[index].length, entry + 8);
+  header.writeUInt32LE(offset, entry + 12);
+  offset += images[index].length;
+});
+await writeFile(
+  new URL("icon.ico", assets),
+  Buffer.concat([header, ...images]),
+);