Design: Text and SVG draw INTO the open sketch instead of beside it

Mirror of snaporca 1fb7786d9a (DesignPanel.cpp and DesignCanvas.cpp applied as patches;
parity 30 / 16, shared files byte-identical).

With a sketch open, Text/SVG outlines become ordinary Line entities via push_closed_lines()
instead of a separate Sketch feature carrying rigid imported_regions — so the letters can
be constrained, trimmed and extruded like anything drawn by hand. The buttons and offer
actions arm Select first when in Sketch mode, since begin_sketch() does not run until a
tool is armed.

add_imported_regions() calls reset_autoedit(): without it the glyph contours entered the
draw-then-edit queue and opened a Length field on the first segment, which freezes the
canvas. Caught on the rig, not by reading.

No sketch open: unchanged — a new Sketch feature, still dropped on a picked face.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LyRwbuq6fjn3VV9U9UvhBM

src/slic3r/GUI/DesignCanvas.cpp

@@ -389,6 +389,14 @@ void DesignCanvas::set_sketch_construction(bool c)
     m_sketch_tool.set_construction(c);
 }
 
+bool DesignCanvas::add_sketch_regions(
+    const std::vector<std::vector<std::vector<Vec2d>>>& regions)
+{
+    const bool ok = m_sketch_tool.add_imported_regions(regions);
+    if (ok) request_repaint();
+    return ok;
+}
+
 void DesignCanvas::set_sketch_polygon_sides(int n)
 {
     m_sketch_tool.set_polygon_sides(n);