ocs_doc_api: Phase 0 + Phase 2a (sweep profiles, non-solid transform, full 2D curves)

Phase 0 (outstanding supported-family methods):
- add_vertex on LwPolyline (insert vertex, out-of-range validation).
- extrude / revolve from profiles (entity_to_profile_curves: Line/Circle/Arc/
  LwPolyline straight-segment conversion -> geom2d::Curve -> brep::extrude/revolve).
- non-solid transform + transform_many via acadrust geometry
  (transform_entity_geometry for Line/Circle/Arc/Point/LwPolyline).
- ensure_transformable broadened accordingly (all-or-nothing pre-validation).

Phase 2a (full 2D curve families): ArcCurve/Ellipse/Spline/Ray/XLine.
- Curve2Spec extended (Arc/Ellipse/Spline/Ray/XLine) + create_arc/create_ellipse/
  create_spline/create_ray/create_xline facade constructors + handle types.
- entity_kind_name, entity_bounds (Arc coarse, Ellipse major-axis, Spline bbox;
  Ray/XLine unbounded), transform_entity_geometry, ensure_transformable extended.
- spec/entities.toml families; api_reference.md + binding_schema.json regenerated.

Tests: +6 doc_api integration tests (phase0_*, phase2_*) -> 598 host lib green.
IMPLEMENTATION.md updated (Phase 0 done, Phase 2a done / 2b remaining).

crates/ocs_doc_api/src/gen/binding_schema.json

@@ -152,6 +152,41 @@
       "handle": "Point",
       "methods": [],
       "name": "Point"
+    },
+    {
+      "acadrust_variant": "Arc",
+      "collection": "curves",
+      "handle": "ArcCurve",
+      "methods": [],
+      "name": "Arc"
+    },
+    {
+      "acadrust_variant": "Ellipse",
+      "collection": "curves",
+      "handle": "Ellipse",
+      "methods": [],
+      "name": "Ellipse"
+    },
+    {
+      "acadrust_variant": "Spline",
+      "collection": "curves",
+      "handle": "Spline",
+      "methods": [],
+      "name": "Spline"
+    },
+    {
+      "acadrust_variant": "Ray",
+      "collection": "curves",
+      "handle": "Ray",
+      "methods": [],
+      "name": "Ray"
+    },
+    {
+      "acadrust_variant": "XLine",
+      "collection": "curves",
+      "handle": "XLine",
+      "methods": [],
+      "name": "XLine"
     }
   ],
   "layouts": {