Implement Da Vinci CRD coverage requirements discovery via CDS Hooks to surface prior auth and documentation needs at point of care

Verified steps

1. Review the Da Vinci CRD IG (hl7.org/fhir/us/davinci-crd) to understand the supported CDS Hooks (order-sign, order-select, encounter-start, encounter-discharge, appointment-book) and the prefetch template requirements for each hook.
2. Register the CRD service with the EHR's CDS Hooks discovery endpoint ([base]/cds-services) and configure the service to handle the appropriate hook types with the required prefetch template for patient demographics, coverage, and the ordered resource.
3. When a hook fires, extract the requested service (MedicationRequest, ServiceRequest, DeviceRequest, or Appointment) from the hook context, and query the payer's coverage rules engine to determine if prior authorization is required.
4. Return a CDS Hooks response with appropriate card types: an information card if documentation is required, a suggestion card if a covered alternative exists, an external link card for payer portal links, or a system-action card to automatically update the order.
5. Implement the required card attributes (summary, detail, indicator, source) and for suggestion cards include the suggested FHIR resource changes conforming to the CRD card type specifications.
6. Handle the case where coverage cannot be determined (e.g., no matching coverage found) by returning an informational card rather than a false-negative 'no requirements' response.