Map Ole2Frame as update-only with the embedded object preserved

Frame corners and the aspect lock are scriptable; the opaque storage and
envelope are excluded and refused on edit. The audit embeds a real PNG
through OCS's own builder and proves it survives DWG and DXF byte-for-byte.
Python creation stays a follow-up.

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

crates/ocs_plugin_api/build.rs

@@ -793,6 +793,7 @@ fn generate_entity_coverage(out_dir: &Path, registry: &TypeRegistry) {
                     | ("Helix", _)
                     | ("RasterImage", _)
                     | ("Wipeout", _)
+                    | ("Ole2Frame", _)
                     | ("Underlay", _)
                     | ("Viewport", _)
                     | ("ViewBorder", _)