Design: port the Orca-widget rebuild and the mouse-press fix from snaporca

Mirrors snaporca-cad a016dffb48 + 4b828c4798 so the two forks do not drift:

- Sidebar on Orca's widget set: ComboBox for all 25 pickers, StaticBox
  frames for the tool cards / feature tree / bodies list, framed double
  spins, and no stack of full-width action buttons (Prepare's left panel
  is parameters only).
- Toolbar: document group + undo/redo + mode-gated tools, commit far
  right, ordered via keyed slots, at Prepare's 40 px / 4 px geometry.
- Polygon options and a new Move/Rotate card (distance, axis, angle) in
  the sidebar instead of inline in the toolbar row.
- DesignSketchTool: stop consuming the LeftDown over a solid. Orca starts
  a rotate drag on the press, so swallowing it killed orbit/pan whenever a
  body was on screen. The pick now resolves on LeftUp within 4 px.

DesignSketchTool.{cpp,hpp} were byte-identical across the forks and are
copied verbatim. DesignPanel.cpp needed one hand-merge: mainline's
DropDown is Item-based (DropDown::Item{text,tip,icon}, DropDown(items&))
where snaporca passes parallel vectors, so feat_dropdown/ToolFlyout keep
the mainline form. Checked field-by-field against this fork's
Widgets/DropDown.hpp.

scripts/docker-iter-build.sh: mount the root CMakeLists.txt and cmake/
rather than inheriting the baked copies, which silently drops the
SLIC3R_CAD gate, and stop defaulting to snaporca's build volume - sharing
it made the two forks overwrite each other's cache and binary.

NOT COMPILED. This fork needs Eigen 5.0.1 (find_package(Eigen3 5.0.1
REQUIRED)) while the available snaporca-deps image supplies 3.3, so it
needs its own deps build to verify. The behaviour above was verified only
on the snaporca side.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BVzKmX6Y1aEteit1HTXG4Q

src/slic3r/GUI/DesignSketchTool.cpp

@@ -7641,7 +7641,21 @@ bool DesignSketchTool::on_mouse(wxMouseEvent& evt, GLCanvas3D& canvas)
                 return true;
             }
         }
-        if (!evt.LeftDown()) return false;
+        // Click vs drag. Consuming the LeftDown here killed camera orbit/pan the moment a
+        // solid was on screen: Orca starts a rotate drag on the press, so swallowing it meant
+        // the canvas never began one. (A SpaceMouse kept working — it never goes through
+        // wxMouseEvent.) Remember the press, let it fall through so the canvas can orbit, and
+        // resolve the pick on release only if the pointer stayed put.
+        if (evt.LeftDown()) {
+            m_pick_press_x = evt.GetX();
+            m_pick_press_y = evt.GetY();
+            m_pick_pending = true;
+            return false;
+        }
+        if (!(evt.LeftUp() && m_pick_pending)) return false;
+        m_pick_pending = false;
+        if (std::abs(evt.GetX() - m_pick_press_x) + std::abs(evt.GetY() - m_pick_press_y) > 4)
+            return false;   // it was a drag: the canvas already orbited, don't also select
         // Committed-sketch loop pick is computed FIRST. A click that lands on a loop's
         // STROKE (edge) selects that loop even when it lies on a solid face — so a sketch
         // drawn ON a face can be selected and extruded/cut (Onshape engraving workflow).