Complete PolygonMesh, PolyfaceMesh and Mesh host model coverage

Maps all three mesh kinds with host validation of grid counts, face indices
and edge topology, and skips sub-record common data in the generator.
A shared run_mesh_lifecycle driver passes the full gate for each kind,
including DWG and DXF reopen with re-edit.

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

crates/ocs_plugin_api/build.rs

@@ -787,6 +787,9 @@ fn generate_entity_coverage(out_dir: &Path, registry: &TypeRegistry) {
                     )
                     | ("MultiLeader", _)
                     | ("Table", _)
+                    | ("PolygonMesh", _)
+                    | ("PolyfaceMesh", _)
+                    | ("Mesh", _)
                     | (
                         "MLine",
                         "flags"