feat(entities): surface remaining 2D + Region fields in properties

Closes out the 2D-entity audit (and the Region partner that ships next
to Solid3D / Body). Round-trip-only metadata fields plus a few editable
ones gain Properties-panel rows so the values the parser populates are
visible and don't get silently dropped on save:

- Hatch: seed_points count, pixel_size, normal
- Polyline2D: smooth_surface, default_start_width, default_end_width,
  thickness, normal (with editors for the widths/thickness)
- Region: uid, silhouettes (shared file with Solid3D / Body)
- Underlay: clip_inverted
- RasterImage: class_version, definition_handle, definition_reactor_handle
- Wipeout: class_version, clip_mode, definition_handle,
  definition_reactor_handle
- Leader: annotation_handle, override_color
- Tolerance: dimension_style_name, dimension_style_handle, dimension_gap,
  text_height (editable), direction, normal
- MLine: style_handle, style_element_count, justification picker
- Ole2Frame: version, source_application, binary_data size, dwg_mode,
  dwg_trailing_byte, is_paper_space
- Viewport: snap_base/spacing/angle, twist_angle, front/back clip Z,
  circle_sides, grid_flags, grid_major, base_ucs_handle, ucs_ortho_type,
  background_handle, shade_plot_handle, visual_style_handle,
  default_lighting, default_lighting_type, ambient_color (with editors
  for the snap / clip / circle_sides values)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/entities/polyline.rs

@@ -347,11 +347,29 @@ impl Grippable for Polyline2D {
 
 impl PropertyEditable for Polyline2D {
     fn geometry_properties(&self, _text_style_names: &[String]) -> PropSection {
+        let smooth = match self.smooth_surface {
+            acadrust::entities::SmoothSurfaceType::None => "None",
+            acadrust::entities::SmoothSurfaceType::QuadraticBSpline => "Quadratic",
+            acadrust::entities::SmoothSurfaceType::CubicBSpline => "Cubic",
+            acadrust::entities::SmoothSurfaceType::Bezier => "Bezier",
+        };
         PropSection {
             title: "Geometry".into(),
             props: vec![
                 ro("Vertices", "vertices", self.vertices.len().to_string()),
                 edit("Elevation", "pl2_elevation", self.elevation),
+                edit("Default Start W", "pl2_start_w", self.start_width),
+                edit("Default End W", "pl2_end_w", self.end_width),
+                edit("Thickness", "pl2_thickness", self.thickness),
+                ro("Smooth Surface", "pl2_smooth", smooth),
+                ro(
+                    "Normal",
+                    "pl2_normal",
+                    format!(
+                        "{:.3}, {:.3}, {:.3}",
+                        self.normal.x, self.normal.y, self.normal.z
+                    ),
+                ),
                 Property {
                     label: "Closed".into(),
                     field: "pl2_closed",
@@ -383,6 +401,25 @@ impl PropertyEditable for Polyline2D {
                     self.elevation = v;
                 }
             }
+            "pl2_start_w" => {
+                if let Ok(v) = value.trim().parse::<f64>() {
+                    if v >= 0.0 {
+                        self.start_width = v;
+                    }
+                }
+            }
+            "pl2_end_w" => {
+                if let Ok(v) = value.trim().parse::<f64>() {
+                    if v >= 0.0 {
+                        self.end_width = v;
+                    }
+                }
+            }
+            "pl2_thickness" => {
+                if let Ok(v) = value.trim().parse::<f64>() {
+                    self.thickness = v;
+                }
+            }
             _ => {}
         }
     }