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/src/gen/api_reference.md

@@ -18,6 +18,7 @@ B-rep solid. Host resolves bodies via the solid_models cache (lift-on-miss from
 - **create_wedge**(`origin: [f64; 3], size: [f64; 3]`) -> `Solid`
 - **extrude**(`profile: EntityRef, direction: [f64; 3]`) -> `Solid`
 - **revolve**(`profile: EntityRef, pivot: [f64; 3], axis: [f64; 3], angle: f64`) -> `Solid`
+- **loft**(`profiles: &[EntityRef]`) -> `Solid`
 
 ### Methods