Merge upstream, including section view and a faster preview

Five commits: a section view for the 3D canvas, a faster G-code preview, user
preset values kept on extruder variants they don't list, debug build CMake
fixes, and a 30 minute timeout on macOS notarization.

Two conflicts, both in GLCanvas3D. The header's were neighboring
declarations, kept from both sides. In the transparent pass, the section view
removed the assemble view's painter block that followed our ghost render;
the ghost render stays where it was, at the end of that pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/slic3r/GUI/MainFrame.cpp

@@ -117,6 +117,7 @@
 #include "NotificationManager.hpp"
 #include "MarkdownTip.hpp"
 #include "NetworkTestDialog.hpp"
+#include "SceneBenchmark.hpp"
 #include "ConfigWizard.hpp"
 #include "Widgets/WebView.hpp"
 #include "DailyTips.hpp"
@@ -2786,6 +2787,10 @@ wxMenu* MainFrame::generate_help_menu()
             dlg.ShowModal();
         });
 
+    if (wxGetApp().is_editor())
+        append_menu_item(helpMenu, wxID_ANY, _L("Benchmark 3D Scene"), _L("Measure how fast the 3D scene renders in Prepare and Preview"),
+            [](wxCommandEvent&) { run_scene_benchmark(); });
+
     helpMenu->AppendSeparator();
 
     append_menu_item(helpMenu, wxID_ANY, _L("Show Tip of the Day"), _L("Show Tip of the Day"), [](wxCommandEvent&) {