Filtering for creatures with an empty rules box can't be done from
`oracle_cards.oracle_text`: that column joins every face together, so an
Adventure card always carries its spell half's text and a naive `oracle_text
= ''` test would exclude exactly the cards worth including.
Derive it at ingest instead, from the front face's own text — the front is the
half that resolves as the creature, and adventure/prepared/transform cards are
all cast from it. Exposed as `vanilla_only` behind its own `has_vanilla`
capability check rather than folded into `has_universes_beyond`, since it
lands in a later reference-schema revision and a db can have one column
without the other. Needs a card-data re-download before it does anything.
Garrett Mills
e3725cee55