feat: add OLE2Frame interactivity + fix Shape rotation from DXF

OLE2Frame: full TruckConvertible/Grippable/PropertyEditable/Transformable
impls in src/entities/ole2frame.rs — grips on corners + center, properties
panel, translate/scale transforms.

Shape: rotation (DXF code 50) now converted degrees→radians on load in
fix_dxf_dimension_rotations(), matching Dimension and Attribute behaviour.

All ❌ gaps resolved. Remaining: Viewport GPU scissor, LWPolyline plinegen.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/entities/mod.rs

@@ -13,6 +13,7 @@ pub mod lwpolyline;
 pub mod mesh;
 pub mod mline;
 pub mod mtext;
+pub mod ole2frame;
 pub mod point;
 pub mod polyline;
 pub mod raster_image;