Get card preparation steps and missing context; missing context creates no records or links

Permission: card.holder.preparation. Query with cardChannelId, cardType (virtual by default) and the context fields advertised by the product, currently cardHolderId. Fill missingContextFields first. Read steps[].requirements for conditional material rules. Use steps[].type/id for form-url/files/submit. Only isPrepared=true means all required steps are ready; WAIT/RETRY means poll after retryAfter, not resubmit. Physical shippingRequirements describes later quote input, not a submitted address.