feat: Shape entity support (render + grips + props + transform)

- src/entities/shape.rs: diamond marker at insertion point (SHX glyphs
  cannot be rendered without the binary .shx file, so a placeholder is used)
- Grips: single insertion-point grip
- Properties: Name, Style (read-only), Insert X/Y/Z, Size, Rotation
- Transformable: translate, mirror, scale, rotate
- Registered in entities/mod.rs, entities/traits.rs, app/commands.rs

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

src/app/commands.rs

@@ -3276,6 +3276,7 @@ fn entity_type_name(entity: &acadrust::EntityType) -> &'static str {
         acadrust::EntityType::AttributeEntity(_)    => "ATTRIB",
         acadrust::EntityType::Leader(_)             => "LEADER",
         acadrust::EntityType::Tolerance(_)          => "TOLERANCE",
+        acadrust::EntityType::Shape(_)              => "SHAPE",
         _ => "ENTITY",
     }
 }

src/entities/mod.rs

@@ -18,6 +18,7 @@ pub mod polyline;
 pub mod raster_image;
 pub mod underlay;
 pub mod ray;
+pub mod shape;
 pub mod solid;
 pub mod spline;
 pub mod text;

src/entities/shape.rs

@@ -0,0 +1,130 @@
+// SHAPE entity — reference to an .SHX shape-file glyph.
+//
+// Since .SHX binary files are not parsed, we render a small diamond marker
+// at the insertion point (same approach as unknown/unsupported entities).
+// The shape_name and style_name are surfaced as read-only properties.
+
+use acadrust::entities::Shape;
+use glam::Vec3;
+
+use crate::command::EntityTransform;
+use crate::entities::common::{ro_prop as ro, edit_prop as edit, square_grip};
+use crate::entities::traits::{Grippable, PropertyEditable, Transformable, TruckConvertible};
+use crate::scene::acad_to_truck::{TruckEntity, TruckObject};
+use crate::scene::object::{GripApply, GripDef, PropSection};
+use crate::scene::wire_model::SnapHint;
+use crate::scene::transform;
+
+// ── Marker geometry ───────────────────────────────────────────────────────────
+
+/// Small diamond marker at the shape insertion point.
+fn shape_marker(ox: f32, oy: f32, oz: f32, size: f32) -> Vec<[f32; 3]> {
+    let s = size * 0.5;
+    vec![
+        [ox,     oy + s, oz],  // top
+        [ox + s, oy,     oz],  // right
+        [ox,     oy - s, oz],  // bottom
+        [ox - s, oy,     oz],  // left
+        [ox,     oy + s, oz],  // close
+        [f32::NAN; 3],
+    ]
+}
+
+// ── TruckConvertible ──────────────────────────────────────────────────────────
+
+impl TruckConvertible for Shape {
+    fn to_truck(&self, _document: &acadrust::CadDocument) -> Option<TruckEntity> {
+        let ox = self.insertion_point.x as f32;
+        let oy = self.insertion_point.y as f32;
+        let oz = self.insertion_point.z as f32;
+        let size = (self.size as f32).abs().max(0.5);
+
+        let snap_pt = Vec3::new(ox, oy, oz);
+        let pts = shape_marker(ox, oy, oz, size);
+
+        Some(TruckEntity {
+            object: TruckObject::Lines(pts),
+            snap_pts: vec![(snap_pt, SnapHint::Insertion)],
+            tangent_geoms: vec![],
+            key_vertices: vec![[ox, oy, oz]],
+        })
+    }
+}
+
+// ── Grippable ─────────────────────────────────────────────────────────────────
+
+impl Grippable for Shape {
+    fn grips(&self) -> Vec<GripDef> {
+        vec![square_grip(
+            0,
+            Vec3::new(
+                self.insertion_point.x as f32,
+                self.insertion_point.y as f32,
+                self.insertion_point.z as f32,
+            ),
+        )]
+    }
+
+    fn apply_grip(&mut self, grip_id: usize, apply: GripApply) {
+        if grip_id == 0 {
+            match apply {
+                GripApply::Translate(d) => {
+                    self.insertion_point.x += d.x as f64;
+                    self.insertion_point.y += d.y as f64;
+                    self.insertion_point.z += d.z as f64;
+                }
+                GripApply::Absolute(p) => {
+                    self.insertion_point.x = p.x as f64;
+                    self.insertion_point.y = p.y as f64;
+                    self.insertion_point.z = p.z as f64;
+                }
+            }
+        }
+    }
+}
+
+// ── PropertyEditable ──────────────────────────────────────────────────────────
+
+impl PropertyEditable for Shape {
+    fn geometry_properties(&self, _text_style_names: &[String]) -> PropSection {
+        PropSection {
+            title: "Geometry".into(),
+            props: vec![
+                ro("Name",     "shp_name",  self.shape_name.clone()),
+                ro("Style",    "shp_style", self.style_name.clone()),
+                edit("Insert X", "shp_ix",  self.insertion_point.x),
+                edit("Insert Y", "shp_iy",  self.insertion_point.y),
+                edit("Insert Z", "shp_iz",  self.insertion_point.z),
+                edit("Size",     "shp_sz",  self.size),
+                edit("Rotation","shp_rot",  self.rotation.to_degrees()),
+            ],
+        }
+    }
+
+    fn apply_geom_prop(&mut self, field: &str, value: &str) {
+        let Ok(v) = value.trim().parse::<f64>() else { return };
+        match field {
+            "shp_ix"  => self.insertion_point.x = v,
+            "shp_iy"  => self.insertion_point.y = v,
+            "shp_iz"  => self.insertion_point.z = v,
+            "shp_sz"  => self.size = v.max(0.001),
+            "shp_rot" => self.rotation = v.to_radians(),
+            _ => {}
+        }
+    }
+}
+
+// ── Transformable ─────────────────────────────────────────────────────────────
+
+impl Transformable for Shape {
+    fn apply_transform(&mut self, t: &EntityTransform) {
+        transform::apply_standard_entity_transform(self, t, |entity, p1, p2| {
+            transform::reflect_xy_point(
+                &mut entity.insertion_point.x,
+                &mut entity.insertion_point.y,
+                p1,
+                p2,
+            );
+        });
+    }
+}

src/entities/traits.rs

@@ -62,6 +62,7 @@ impl EntityTypeOps for EntityType {
             EntityType::Leader(leader) => TruckConvertible::to_truck(leader, document),
             EntityType::MultiLeader(ml) => TruckConvertible::to_truck(ml, document),
             EntityType::Underlay(ul) => TruckConvertible::to_truck(ul, document),
+            EntityType::Shape(shp) => TruckConvertible::to_truck(shp, document),
             _ => None,
         }
     }
@@ -100,6 +101,7 @@ impl EntityTypeOps for EntityType {
             EntityType::Dimension(dim) => Grippable::grips(dim),
             EntityType::Hatch(hatch) => Grippable::grips(hatch),
             EntityType::Underlay(ul) => Grippable::grips(ul),
+            EntityType::Shape(shp) => Grippable::grips(shp),
             _ => vec![],
         }
     }
@@ -230,6 +232,10 @@ impl EntityTypeOps for EntityType {
                 ul,
                 text_style_names,
             )),
+            EntityType::Shape(shp) => Some(PropertyEditable::geometry_properties(
+                shp,
+                text_style_names,
+            )),
             _ => None,
         }
     }
@@ -270,6 +276,7 @@ impl EntityTypeOps for EntityType {
             EntityType::Leader(leader) => PropertyEditable::apply_geom_prop(leader, field, value),
             EntityType::MultiLeader(ml) => PropertyEditable::apply_geom_prop(ml, field, value),
             EntityType::Underlay(ul) => PropertyEditable::apply_geom_prop(ul, field, value),
+            EntityType::Shape(shp) => PropertyEditable::apply_geom_prop(shp, field, value),
             _ => {}
         }
     }
@@ -308,6 +315,7 @@ impl EntityTypeOps for EntityType {
             EntityType::Dimension(dim) => Grippable::apply_grip(dim, grip_id, apply),
             EntityType::Hatch(hatch) => Grippable::apply_grip(hatch, grip_id, apply),
             EntityType::Underlay(ul) => Grippable::apply_grip(ul, grip_id, apply),
+            EntityType::Shape(shp) => Grippable::apply_grip(shp, grip_id, apply),
             _ => {}
         }
     }
@@ -346,6 +354,7 @@ impl EntityTypeOps for EntityType {
             EntityType::Leader(leader) => Transformable::apply_transform(leader, t),
             EntityType::MultiLeader(ml) => Transformable::apply_transform(ml, t),
             EntityType::Underlay(ul) => Transformable::apply_transform(ul, t),
+            EntityType::Shape(shp) => Transformable::apply_transform(shp, t),
             _ => {}
         }
     }