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/facade.rs

@@ -452,6 +452,13 @@ impl SolidCollection {
             .ok_or_else(|| ApiError::Transport("revolve returned no id".into()))?;
         Ok(Solid::new(self.session.clone(), id))
     }
+    /// Loft a solid through >= 2 profile entities (polylines/circles/arcs).
+    pub fn loft(&self, profiles: &[impl HasId]) -> ApiResult<Solid> {
+        let ids: Vec<ObjectId> = profiles.iter().map(|p| p.id()).collect();
+        let receipt = self.session.apply_op(Operation::Loft { profiles: ids })?;
+        let id = receipt.outcome.and_then(|o| o.new_id()).ok_or_else(|| ApiError::Transport("loft returned no id".into()))?;
+        Ok(Solid::new(self.session.clone(), id))
+    }
 }
 
 #[derive(Clone)]