feat(api): name the file qrcode.[format] to match the front-end naming

server/api/index.ts

@@ -22,5 +22,9 @@ export default defineEventHandler(async (event) => {
 
   const image = canvas.toBuffer(format);
   event.node.res.setHeader("Content-Type", `image/${format}`);
+  event.node.res.setHeader(
+    "Content-Disposition",
+    `filename="qrcode.${format}"`,
+  );
   return image;
 });