BankFeedback lived under entities/bank-card/ui but pulled apiErrorCode
from @/shared/api, which dragged the entire api layer (openapi-fetch,
openapi-react-query, @tanstack/react-query, client, problem-details,
resource-query) into any Storybook story that imported a sibling
view, breaking stories-must-not-reach-application-data.
Move the local 'extract code from unknown' helper into the entity
and consume it from BankFeedback. The shared helper stays in
shared/api for the rest of the app.
