ocs_doc_api: outstanding methods — loft + bulge-arc polyline profiles

- Loft{profiles} op (append-only); executor resolves each profile to curve sets
  all-or-nothing; backend loft() -> brep::loft on XY plane; facade solids().loft.
- entity_to_profile_curves: convert LwVertex.bulge to geom2d::Curve::Arc via
  bulge_arc_segment (theta = 4*atan(bulge)), so bulged polyline profiles sweep
  correctly instead of erroring Unsupported.
- spec loft; api_reference + binding_schema regenerated; mocks + baseline.
- Tests: loft_two_profiles_produces_solid, bulge_arc_polyline_profile_converts_to_arc
  (semicircle radius=5 for bulge=1) -> 612 host lib + 3 consistency green.

crates/ocs_doc_api/spec/entities.toml

@@ -68,6 +68,11 @@ name = "revolve"
 args = [{ name = "profile", ty = "EntityRef" }, { name = "pivot", ty = "[f64; 3]" }, { name = "axis", ty = "[f64; 3]" }, { name = "angle", ty = "f64" }]
 op = "Revolve"
 
+[[family.constructor]]
+name = "loft"
+args = [{ name = "profiles", ty = "&[EntityRef]" }]
+op = "Loft"
+
 [[family.method]]
 name = "intersect"
 kind = "op"