scan now stashes the raw Unit_Key_RO.inf + MKB bytes on AacsState (via
resolve_vid_only, the disable_keydb path), so an external key-resolver can
derive unit keys from a resolved VUK without re-reading the disc — the
foundation for moving lookup/derivation out of libfreemkv. Additive: the keydb
path is untouched, all existing constructors default the new fields empty.
584 lib tests green. Builds on the KeyOrigin rename + the Key/decrypt_with API.