fix: correct polyline arc direction, text precision, Face3D edge color, buffer chunking

- fix: polyline arc center sign was inverted (- → +) causing arcs to render on the
  wrong side in LwPolyline and Polyline2D
- fix: store glyph strokes in local space with f64 origin so world_offset subtraction
  uses f64 precision; prevents blocky text at large UTM coordinates
- fix: Face3D fill darkened to 45% so edge wires are visually distinct from fill
- fix: wire batch vertex buffer chunked to 256 MB GPU limit (was panic on large files)
- fix: gpu_face3d_edges changed from Option<WireGpu> to Vec<WireGpu> to support chunks

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

src/entities/attribute.rs

@@ -5,7 +5,7 @@ use crate::command::EntityTransform;
 use crate::entities::common::{edit_prop as edit, ro_prop as ro, square_grip};
 use crate::entities::text_support::resolve_text_style;
 use crate::entities::traits::{Grippable, PropertyEditable, Transformable, TruckConvertible};
-use crate::scene::acad_to_truck::{TruckEntity, TruckObject};
+use crate::scene::acad_to_truck::{TextStroke, TruckEntity, TruckObject};
 use crate::scene::object::{GripApply, GripDef, PropSection};
 use crate::scene::wire_model::SnapHint;
 use crate::scene::{cxf, transform};
@@ -26,8 +26,9 @@ impl TruckConvertible for AttributeDefinition {
             self.default_value.clone()
         };
         let wf = (self.width_factor as f32).max(0.01);
+        let origin = [self.insertion_point.x, self.insertion_point.y];
         let strokes = cxf::tessellate_text_ex(
-            [self.insertion_point.x as f32, self.insertion_point.y as f32],
+            [0.0, 0.0],
             self.height as f32,
             self.rotation as f32,
             wf * resolved.width_factor.max(0.01),
@@ -36,7 +37,7 @@ impl TruckConvertible for AttributeDefinition {
             &display,
         );
         Some(TruckEntity {
-            object: TruckObject::Text(strokes),
+            object: TruckObject::Text(vec![TextStroke { strokes, origin }]),
             snap_pts: vec![(snap_pt, SnapHint::Insertion)],
             tangent_geoms: vec![],
             key_vertices: vec![],
@@ -128,8 +129,9 @@ impl TruckConvertible for AttributeEntity {
         );
         let resolved = resolve_text_style(&self.text_style, document);
         let wf = (self.width_factor as f32).max(0.01);
+        let origin = [self.insertion_point.x, self.insertion_point.y];
         let strokes = cxf::tessellate_text_ex(
-            [self.insertion_point.x as f32, self.insertion_point.y as f32],
+            [0.0, 0.0],
             self.height as f32,
             self.rotation as f32,
             wf * resolved.width_factor.max(0.01),
@@ -138,7 +140,7 @@ impl TruckConvertible for AttributeEntity {
             &self.value,
         );
         Some(TruckEntity {
-            object: TruckObject::Text(strokes),
+            object: TruckObject::Text(vec![TextStroke { strokes, origin }]),
             snap_pts: vec![(snap_pt, SnapHint::Insertion)],
             tangent_geoms: vec![],
             key_vertices: vec![],