This endpoint returns the current set of photos required or uploaded for a
given claim. Each call generates fresh presigned URLs for the photos so they
can be downloaded directly from Extend's storage.

Important:

• Presigned URLs returned by this endpoint are short-lived. Fetch the
  response and use the URLs immediately — do not cache them.

• Requests are scoped to the calling merchant. A claim that does not belong
  to the caller's store will return 403: Forbidden.

• If the claim exists but has no photos, the endpoint returns
  200 with an empty photoDetails array (not a 404).