fix: ship sharp binaries for Windows arm64 builds

scripts/install-windows-sharp.cjs

@@ -0,0 +1,26 @@
+const fs = require("node:fs");
+const path = require("node:path");
+const { execFileSync } = require("node:child_process");
+
+function findPackage(start) {
+  let directory = path.dirname(start);
+  while (directory !== path.dirname(directory)) {
+    const manifest = path.join(directory, "package.json");
+    if (fs.existsSync(manifest)) return JSON.parse(fs.readFileSync(manifest));
+    directory = path.dirname(directory);
+  }
+  throw new Error("Could not locate the installed sharp package manifest");
+}
+
+// The build runs on x64 but ships arm64 and ia32 too, so npm ci alone
+// only installs the x64 binary.
+const sharpPackage = findPackage(require.resolve("sharp"));
+const packages = [
+  "@img/sharp-win32-arm64",
+  "@img/sharp-win32-ia32",
+  "@img/sharp-win32-x64",
+].map((name) => `${name}@${sharpPackage.optionalDependencies[name]}`);
+
+execFileSync("npm.cmd", ["install", "--force", "--no-save", ...packages], {
+  stdio: "inherit",
+});