Map RasterImage with host-created image definitions

Scripts name an image file; the host reads its pixel size, creates and links
the ImageDefinition and derives size and the default clip boundary.
staged_python_raster_image_lifecycle_over_real_ipc passes every gate in OCS
with a real PNG. ACAD_IMAGE_DICT and reactor linkage are not created, so the
kind is recorded as integration-tested.

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

crates/ocs_plugin_api/build.rs

@@ -791,6 +791,7 @@ fn generate_entity_coverage(out_dir: &Path, registry: &TypeRegistry) {
                     | ("PolyfaceMesh", _)
                     | ("Mesh", _)
                     | ("Helix", _)
+                    | ("RasterImage", _)
                     | (
                         "MLine",
                         "flags"