Complete Dimension host model coverage for all nine subtypes

Adds a hand-written flat Dimension model to the adapter (manifest
manual_kinds hook) and a synthetic-property section to the host coverage
policy. The host derives actual_measurement and the base definition point on
scripted create/edit. staged_python_dimension_lifecycle_over_real_ipc passes
the full gate for every subtype including DWG and DXF reopen. Python ints are
now accepted for coordinates and angles.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

crates/ocs_plugin_api/build.rs

@@ -21,6 +21,13 @@ use entity_coverage_schema::{
     EntityCoverageCatalog, EntityKindCoverage, EntityScope, ModelAccess, PropertyCoverage,
 };
 
+#[derive(serde::Deserialize)]
+struct SyntheticProperty {
+    name: String,
+    type_id: String,
+    access: String,
+}
+
 #[derive(serde::Deserialize)]
 struct EntityCoveragePolicy {
     internal_kinds: Vec<String>,
@@ -28,6 +35,10 @@ struct EntityCoveragePolicy {
     editable: BTreeMap<String, Vec<String>>,
     readable: BTreeMap<String, Vec<String>>,
     aliases: BTreeMap<String, BTreeMap<String, String>>,
+    /// Properties for kinds whose payload is a nested enum (Dimension), where
+    /// the traced variant has no single field list to map.
+    #[serde(default)]
+    synthetic: BTreeMap<String, Vec<SyntheticProperty>>,
 }
 
 fn main() {
@@ -802,6 +813,19 @@ fn generate_entity_coverage(out_dir: &Path, registry: &TypeRegistry) {
                 model_access: access,
             });
         }
+        for synthetic in policy.synthetic.get(kind).into_iter().flatten() {
+            let writable = synthetic.access == "read_write";
+            properties.push(PropertyCoverage {
+                name: synthetic.name.clone(),
+                source_path: format!("<subtype>.{}", synthetic.name),
+                type_id: synthetic.type_id.clone(),
+                optional: false,
+                is_sequence: false,
+                snapshot_readable: true,
+                validation: if writable { "transaction_geometry" } else { "none" }.into(),
+                model_access: if writable { ModelAccess::ReadWrite } else { ModelAccess::ReadOnly },
+            });
+        }
         assert!(
             unresolved.is_empty(),
             "{kind} has coverage keys absent from registry: {unresolved:?}"