Map Light; record SectionSymbol as blocked

Light placement, intensity, colour, attenuation and shadow fields are
writable with host validation. staged_python_light_lifecycle_over_real_ipc
passes every gate except DXF cast_shadows, pinned by a canary.
SectionSymbol is recorded as blocked: it needs host-created style and view
representation objects and its raw point counts have no documented
derivation.

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

crates/ocs_plugin_api/build.rs

@@ -796,6 +796,7 @@ fn generate_entity_coverage(out_dir: &Path, registry: &TypeRegistry) {
                     | ("Underlay", _)
                     | ("Viewport", _)
                     | ("ViewBorder", _)
+                    | ("Light", _)
                     | (
                         "MLine",
                         "flags"