Returns a single card transaction by id. Visible to admins, holders of the
card_transactions_manage permission, or the cardholder the transaction
belongs to.

The response includes the transaction's transaction_labels and the computed
fields commission_id, type, amount_formatted, and
target_amount_formatted. The internal embedding vector is never exposed.

Multi-provider note. Amounts are Cardda's own reconstruction across issuing
partners (Slash, PLH, Pomelo, etc.): amount_in_clp is the CLP reconversion at
settlement, and for some vendors the balance/decline context is derived from the
vendor payload rather than a native field. Decline reasons surface in
status_reason.