ocs_doc_api: Phase 2b-c (linear Dimension) — Phase 2 complete

- CreateDimensionLinear(DimensionSpec) op + GetDimensionMeasurement query (append-only).
- backend add_dimension_linear (Dimension::Linear via DimensionLinear::new) +
  dimension_measurement (linear/radius/diameter distance).
- Dimension bounds from measured + definition points; Dimension handle + measurement().
- spec Dimension family; api_reference + binding_schema regenerated; mocks + baseline.
- Test phase2c_dimension_linear_create_measurement_bounds -> 607 host lib + 8 crate
  + 3 consistency green. Phase 2 (full 2D + annotations) is now complete.

crates/ocs_doc_api/tests/spec_wire_consistency.rs

@@ -57,6 +57,7 @@ fn operation_variants() -> Vec<String> {
         Operation::CreateMText(ocs_doc_api::ops::MTextSpec { value: String::new(), insertion_point: [0.0; 3], height: 0.0 }),
         Operation::SetTextContent { id: ObjectId::from_u64(0), value: String::new() },
         Operation::CreateHatch(ocs_doc_api::ops::HatchSpec { boundary: vec![], solid: true }),
+        Operation::CreateDimensionLinear(ocs_doc_api::ops::DimensionSpec { first_point: [0.0; 3], second_point: [0.0; 3], definition_point: [0.0; 3] }),
     ];
     // Derive the variant names by serializing a probe of each and reading the
     // bincode variant index -> name map is not available; instead match by
@@ -83,6 +84,7 @@ fn query_variants() -> Vec<String> {
         Query::GetGeometryRevision,
         Query::GetTextContent { id: ObjectId::from_u64(0) },
         Query::GetHatchBoundary { id: ObjectId::from_u64(0) },
+        Query::GetDimensionMeasurement { id: ObjectId::from_u64(0) },
     ];
     marker
         .iter()
@@ -137,6 +139,7 @@ const OPERATION_BASELINE: &[&str] = &[
     "CreateMText",
     "SetTextContent",
     "CreateHatch",
+    "CreateDimensionLinear",
 ];
 
 /// Recorded baseline of the `Query` variant order.
@@ -149,6 +152,7 @@ const QUERY_BASELINE: &[&str] = &[
     "GetGeometryRevision",
     "GetTextContent",
     "GetHatchBoundary",
+    "GetDimensionMeasurement",
 ];
 
 #[test]