record.to_json serializes through model accessors. Column::Colored
overrides the color accessor to return a Color struct, which serializes
as {"name":"Blue","value":"var(--color-card-default)"} instead of the
raw CSS string.
Two fixes:
- Export raw DB values via record.attributes.slice(*attributes).to_json
- Color.for_value parses legacy JSON format so columns imported from
old exports self-heal when read
Donal McBreen