"""
AAhead library — the real ROM ingest backend (no mocks).

`systems`  : the system table (catalog name ↔ /roms folder ↔ ROM extensions).
`ingest`   : scan → identify → match → plan → apply (reversible) → undo.

Pure Python, no pygame: the GUI calls in, and the future desktop "iTunes"
companion writes the very same manifest contract this module reads.
"""
