Add assignment regrade update flow

frontend/app/globals.css

@@ -210,6 +210,17 @@ textarea.input {
   background: rgba(255, 255, 255, 0.7);
 }
 
+.edit-banner {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  gap: 12px;
+  padding: 12px 14px;
+  border-radius: 14px;
+  border: 1px dashed rgba(31, 29, 26, 0.3);
+  background: rgba(15, 76, 92, 0.08);
+}
+
 .preview {
   width: 100%;
   border-radius: 16px;