Get outside medications (out-of-band, e.g. filled at an online/outside pharmacy) recorded on a patient for tracking. Intentionally separate from inventory and Rx governance — there may be no matching inventory item. NOTE: the "external-medications" route (and the external_medication_requests table) are kept stable across the OutsideMedication rename — the rename freed "MedicationRequest" for the stateful request entity (docs/medication-request-lifecycle-design.md).