Suspends an identification and blocks all associated services for every account linked to it. This is the escalation endpoint for when an end user must be stopped immediately (e.g. suspected fraud). A vault-scoped variant is also available at POST /vaults/{vault_id}/identifications/{identification_id}/block.
Blocked services are: - trades - fiat_payment - blockchain_payment - card_payment - internal_settlement (only when the feature is enabled for the vault)
Effects: - The identification status is set to blocked. - Each affected account fires an account_locked webhook, so the client is notified. - When a reason is provided, it is stored on every blocked service for auditability, and the
block is attributed to the API caller (blocked_by).

Idempotent: blocking an identification that is already blocked succeeds and returns the current state. This endpoint never unblocks anything.