submit: restore Validating... toast on click

submit.py

@@ -200,6 +200,16 @@ def handle_submit(
     if form_err is not None:
         raise gr.Error(form_err)
 
+    # Immediate ack on click. The eval itself (after queuing) is the
+    # slow part, so hint at the wall time up front so the user knows
+    # what to expect instead of waiting on a silent button. Restored
+    # after commit ed2a486 dropped the bookend toast in favour of a
+    # button-progress tracker.
+    gr.Info(
+        "Validating submission... evaluation usually takes "
+        "~1 minute after queuing."
+    )
+
     zip_path = Path(zip_file.name)
 
     # The tempdir lives only for the cheap-sync validation pass