ocs_doc_api: Phase 2b-b (Hatch)

- CreateHatch(HatchSpec) op + GetHatchBoundary query (append-only).
- HatchSpec{boundary: Vec<[f64;2]>, solid}; executor validates >= 3 boundary points.
- backend add_hatch (Line-edge BoundaryPath, solid/pattern) + hatch_boundary
  (reconstruct loops from Line edges; non-line edges -> Unsupported).
- Hatch bounds from boundary edges; facade create_hatch + Entity handle.
- spec Hatch family; api_reference + binding_schema regenerated; mocks + baseline.
- Test phase2b_hatch_create_boundary_bounds_delete -> 606 host lib + 8 crate + 3 consistency green.

crates/ocs_doc_api/src/ops.rs

@@ -96,6 +96,16 @@ pub struct MTextSpec {
     pub height: f64,
 }
 
+/// Construction spec for a `HATCH` with a single closed polyline boundary
+/// (straight segments). `solid` selects solid fill vs a pattern (pattern naming
+/// is a later refinement).
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct HatchSpec {
+    /// Closed boundary as an ordered polyline (first==last implied; closed).
+    pub boundary: Vec<[f64; 2]>,
+    pub solid: bool,
+}
+
 /// A rigid similarity (rotation + translation + optional uniform scale/reflection)
 /// as a plain-data mirror of `cadkernel::brep::transform`'s `Placement`
 /// (non-serde). Columns are the new basis axes; `origin` is the translation.
@@ -148,6 +158,7 @@ impl crate::gen::Operation {
             CreateText(_) => "CreateText",
             CreateMText(_) => "CreateMText",
             SetTextContent { .. } => "SetTextContent",
+            CreateHatch(_) => "CreateHatch",
         }
     }
 }