fix: await concurrent attachment uploads

src/pages/Chat/CodingChatPanel.tsx

@@ -392,7 +392,10 @@ export function CodingChatPanel({
         };
       }
     });
-    await Promise.all(workers);
+    const results = await Promise.allSettled(workers);
+    for (const result of results) {
+      if (result.status === 'rejected') throw result.reason;
+    }
     return prepared;
   }, []);