rlmesh_ext_callback_set_tagged_error_payload

Tagged ownership transfer: the library never reads tag or payload bytes. The tag identifies a payload representation/owner domain. The legacy setter records a NULL tag. Use the returned deleter for foreign representations. On success, all outputs are initialized (NULL when empty); outputs must be distinct writable slots. All three are required. A failing call does not consume the payload. A successful take transfers the deleter obligation.

void rlmesh_ext_callback_set_tagged_error_payload(
    void* payload,
    void (*free_payload)(void* payload),
    const void* tag
)