fix: normalize vip98k references for provider limits

lib/ai/providers/vip98k.ts

@@ -644,20 +644,14 @@ async function downloadReferenceImageFromStorage(
 
 async function normalizeReferenceImage(buffer: Buffer, mimeType: string) {
   try {
-    const metadata = await sharp(buffer, { failOn: "none" }).metadata();
-    const pipeline = sharp(buffer, { failOn: "none" })
+    const normalized = await sharp(buffer, { failOn: "none" })
       .rotate()
-      .resize(2048, 2048, { fit: "inside", withoutEnlargement: true });
-    if (metadata.hasAlpha || /png/i.test(mimeType)) {
-      return {
-        buffer: await pipeline.png({ compressionLevel: 6 }).toBuffer(),
-        extension: "png",
-      };
-    }
+      .resize(1920, 1920, { fit: "inside", withoutEnlargement: true })
+      .flatten({ background: "#ffffff" })
+      .jpeg({ quality: 92, chromaSubsampling: "4:4:4", mozjpeg: true })
+      .toBuffer();
     return {
-      buffer: await pipeline
-        .jpeg({ quality: 95, chromaSubsampling: "4:4:4", mozjpeg: true })
-        .toBuffer(),
+      buffer: normalized,
       extension: "jpg",
     };
   } catch (error) {