Add a back_image_uri column to printings, populated during ingest from
a card's second card_faces image (only present for transform/MDFC/
reversible cards — split/adventure cards share one combined image and
correctly get ""). Plumb it through CardRef across every query path
(search, library, filters, deck contents) via the same printing row,
using a shared deterministic ORDER BY so front/back always come from
one printing.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>