fix: project profile name shows stale value after save

After saving in the editor, clear_model_info() empties m_last_payload.
If index.html loads and sends request_3mf_info before the background
on_reload() thread completes — or if on_reload()'s RunScript call is
dropped during webview navigation — the page receives no data and
continues to display the pre-save profile name.

Fall back to update_model_data() when request_3mf_info arrives with an
empty m_last_payload.  This triggers a fresh on_reload() which dispatches
the up-to-date model data directly to the now-loaded page.

Author: BenJule

src/slic3r/GUI/Project.cpp

@@ -389,6 +389,12 @@ void ProjectPanel::OnScriptMessage(wxWebViewEvent& evt)
                 wxGetApp().CallAfter([this, strJS] {
                     RunScript(strJS.ToStdString());
                 });
+            } else {
+                // m_last_payload was cleared (e.g. after a save) and the background
+                // reload may not have finished yet — or its dispatch was dropped during
+                // webview navigation.  Trigger a fresh reload so the new page receives
+                // up-to-date model data once the reload completes.
+                update_model_data();
             }
         }
         else if (strCmd == "request_confirm_save_project") {