FacetReaderPort

• get
  [T](key: FacetKey, payload_type: type[T]) -> T | None
  Read a facet by key, deserializing to the given type
• exists
  (key: FacetKey) -> bool
  Check if a facet exists without deserializing

• InMemoryFacetStore
  from facets
  In-memory facet storage for testing

Not required by any components