mal_anilist_map.cpp — MyAnimeList <-> AniList anime id table

Derived from the manami-project "anime-offline-database"
(https://github.com/manami-project/anime-offline-database), which aggregates
cross-references between anime metadata providers. The table here keeps only
the (myanimelist.net id, anilist.co id) pairs of entries that carry both, and
nothing else from the dataset.

License of the dataset and therefore of this derivative table: Open Database
License (ODbL) v1.0, https://opendatacommons.org/licenses/odbl/1-0/.
The shigoku source code around it is GPL-3.0-or-later; the two coexist the
way ODbL map data ships inside GPL applications. Any redistribution of a
modified table must stay under ODbL and keep this notice.

Regenerate with:

    tools/gen_idmap.py anime-offline-database.jsonl.zst --release <tag>

The release tag and the dataset's own lastUpdate date are recorded at the top
of the generated file.
