Implement Azure DICOM service change feed polling to trigger downstream workflows when new imaging studies arrive

Steps

1. Authenticate to the Azure DICOM service using a Microsoft Entra token with the DICOM Data Reader role assigned to the calling identity
2. Poll the change feed endpoint GET https://MY_DICOM.dicom.azurehealthcareapis.com/v1/changefeed?offset=0&limit=100&includeMetadata=true to retrieve the latest batch of change events
3. Parse the JSON array of change feed entries; each entry contains a sequence number, action (create or delete), studyInstanceUid, seriesInstanceUid, sopInstanceUid, and a metadata block
4. Persist the highest processed sequence number (offset) in durable storage and use it as the offset parameter on the next poll to ensure at-least-once processing without re-processing old events
5. On receipt of a create event, trigger downstream actions such as invoking an AI inference job, updating a FHIR ImagingStudy resource, or sending a notification to the radiology worklist