refactor: Correctly iterate over file parts array in delete operation

src/app/api/delete/route.ts

@@ -50,7 +50,7 @@ export async function POST(request: Request) {
       );
 
       // 3. Delete each message from Discord sequentially to avoid rate limits
-      for (const part of partsRows[0] as FilePart[]) {
+      for (const part of partsRows as FilePart[]) {
         if (!part.discord_message_id) continue;
 
         try {