Dress-up card: say whether Confirm will round the picked edge or the group

The card decides between a single picked edge and a whole face-group from a
viewport pick it never mentioned. With no edge picked the user saw only the
group combo and concluded per-edge rounding did not exist; with an edge picked
the combo still read "All" — the opposite of what Confirm would do.

Adds a Target row that names the actual target and greys the group combo out
while an edge is picked, wired at the same three points Shell already uses:
the selection-changed handler, the re-edit load, and open_tool.

Ported from the Snapmaker fork (33771a0e95). snaporca-40d

src/slic3r/GUI/DesignPanel.hpp

@@ -238,6 +238,7 @@ private:
     // plane + centroid + live depths while the Extrude card is open (self-gates on m_active).
     void       update_extrude_gizmo();
     void       update_fillet_gizmo();     // edge-anchored radius arrow (Dressup card)
+    void       sync_dressup_target();     // Dressup card: show picked edge vs group, gate the combo
     void       update_hole_gizmo();       // footprint circle + diameter/depth arrows (Hole card)
     void       update_thread_gizmo();     // footprint circle + radius/length arrows (Thread card)
     void       update_shell_gizmo();      // inward thickness arrow on the picked face (Shell card)
@@ -592,6 +593,7 @@ private:
     ComboBox*         m_dressup_type{nullptr};
     ComboBox*         m_face_group{nullptr};
     wxSpinCtrlDouble* m_dressup_size{nullptr};
+    wxStaticText*     m_dressup_edge_label{nullptr}; // shows the picked edge, or the group fallback
 
     ComboBox*         m_hole_plane{nullptr};
     wxSpinCtrlDouble* m_hole_diameter{nullptr};