build(deps): bump acadrust to 486c0a9; handle the Helix entity

Pull in this session's acadrust work — the HELIX / ACAD_TABLE read+write,
underlay reader/writer/definition, spline tolerances & tangents, etc. The new
EntityType::Helix variant breaks three exhaustive matches; add its arm to
entity_type_name, the UI-name / DXF-name maps and entity_type_key.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

src/app/helpers.rs

@@ -313,6 +313,7 @@ pub(super) fn entity_type_key(entity: &acadrust::EntityType) -> String {
         Arc(_) => "arc",
         Ellipse(_) => "ellipse",
         Spline(_) => "spline",
+        Helix(_) => "helix",
         LwPolyline(_) | Polyline(_) => "pline",
         Polyline2D(_) => "pline2d",
         Polyline3D(_) => "pline3d",

src/entities/names.rs

@@ -18,6 +18,7 @@ pub fn ui_name(e: &EntityType) -> &'static str {
         EntityType::Arc(_) => "Arc",
         EntityType::Ellipse(_) => "Ellipse",
         EntityType::Spline(_) => "Spline",
+        EntityType::Helix(_) => "Helix",
         EntityType::LwPolyline(_) => "Polyline",
         EntityType::Polyline(_) => "Polyline",
         EntityType::Polyline2D(_) => "Polyline2D",
@@ -77,6 +78,7 @@ pub fn dxf_name(e: &EntityType) -> &'static str {
         EntityType::Dimension(_) => "DIMENSION",
         EntityType::Viewport(_) => "VIEWPORT",
         EntityType::Spline(_) => "SPLINE",
+        EntityType::Helix(_) => "HELIX",
         EntityType::Ellipse(_) => "ELLIPSE",
         EntityType::Point(_) => "POINT",
         EntityType::Ray(_) => "RAY",

src/entities/traits.rs

@@ -111,6 +111,7 @@ pub fn entity_type_name(et: &EntityType) -> &'static str {
         EntityType::Text(_) => "Text",
         EntityType::MText(_) => "MText",
         EntityType::Spline(_) => "Spline",
+        EntityType::Helix(_) => "Helix",
         EntityType::Dimension(_) => "Dimension",
         EntityType::Hatch(_) => "Hatch",
         EntityType::Solid(_) => "Solid",