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/IMPLEMENTATION.md

@@ -112,10 +112,14 @@ Phase 2b (annotations/hatch/dimension typed ops), attributes + nested traversal
 
 | Method | Family | Status | Blocker |
 |---|---|---|---|
-| `loft(sections)` | Solid | not started | multi-profile kernel op + spec |
-| Bulge-arc polyline profiles | Solid sweep | partial | `entity_to_profile_curves` emits straight segments; bulge arcs need arc-segment conversion |
 | `GetCentroid`/`GetVolume` accuracy | Solid | mesh approx | render-mesh LOD tolerance vs query tolerance |
 
+**Completed (outstanding methods):** `loft(profiles)` — `Operation::Loft{profiles}`,
+resolves each profile to curve sets (all-or-nothing), `brep::loft` (`loft_two_profiles_*`
+test). **Bulge-arc polyline profiles** — `entity_to_profile_curves` now converts
+`LwVertex.bulge` to `geom2d::Curve::Arc` via the bulge→arc formula (θ = 4·atan(bulge)),
+so bulged profiles sweep correctly (`bulge_arc_polyline_profile_converts_to_arc` test).
+
 **Completed (Phase 0):** `extrude`, `revolve` (profiles: Line/Circle/Arc/LwPolyline),
 `add_vertex` (polyline), non-solid `transform` + `transform_many` (Line/Circle/Arc/
 Point/LwPolyline). Covered by `phase0_*` tests in `src/app/doc_api.rs`.