Merge upstream main into the IMEX work

Upstream replaced MainFrame's fixed-index TabPosition enum with string-based
page ids ("feat: refactor notebook/tabs to be string based instead of fixed
index based"). The IMEX toolhead-visibility menu item was the only consumer of
that enum left on this branch, so its enable check now compares
m_tabpanel->GetSelectedPageName() against TAB_ID_PREVIEW -- the same form the
neighbouring upstream menu items use.

That mismatch is what broke CI: the branch built on its own, but the merge
commit CI builds no longer had TabPosition declared. No other conflicts.

666/666 tests pass in Release.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/libslic3r/PrintApply.cpp

@@ -560,11 +560,9 @@ static inline bool model_volume_solid_or_modifier(const ModelVolume &mv)
 
 static inline Transform3f trafo_for_bbox(const Transform3d &object_trafo, const Transform3d &volume_trafo)
 {
-    // Orca: Keep the volume's local XY offset for multipart overlap checks, but remove the object's bed placement.
-    Transform3d object_trafo_local = object_trafo;
-    object_trafo_local.translation().x() = 0.;
-    object_trafo_local.translation().y() = 0.;
-    Transform3d m = object_trafo_local * volume_trafo;
+    Transform3d m = object_trafo * volume_trafo;
+    m.translation().x() = 0.;
+    m.translation().y() = 0.;
     return m.cast<float>();
 }