Fix detail stitch long preview format

app/api/agent-workflow/detail-stitch/route.ts

@@ -126,7 +126,7 @@ function buildReferenceFetchUrl(url: string): string {
   return buildImageProxyUrl(url, {
     width: PREVIEW_MAX_WIDTH,
     quality: 82,
-    format: "webp",
+    format: "jpeg",
   });
 }
 
@@ -303,14 +303,15 @@ async function prepareStitch(params: {
     },
   })
     .composite(compositeItems)
-    .webp({
+    .jpeg({
       quality: 76,
-      effort: 4,
+      mozjpeg: true,
+      progressive: true,
     })
     .toBuffer();
 
   const upload = await uploadFile(
-    `detail-stitch-preview-${Date.now()}-${Math.random().toString(36).slice(2, 8)}.webp`,
+    `detail-stitch-preview-${Date.now()}-${Math.random().toString(36).slice(2, 8)}.jpg`,
     bufferToArrayBuffer(previewBuffer),
   );