Returns the full list of audienceList and segment entities available for the given
application, along with the GCS path of the CSV that represents them:

• For audienceList, the gcsPath is the CSV uploaded by the user (already stored on
  the entity).
• For segment, the gcsPath is the deterministic path of the last materialized CSV.
  Segments that have never been materialized (no filterDefinition set yet) are omitted.

gcsPath is only included in the response when the request is an internal request (e.g.
api-gateway internal processes / other channel services); it is omitted for any other caller.

Results are ordered by updatedAt descending (most recently updated first) and can be
paginated with limit/page.

Intended to be consumed by other channel services (email, sms, push, inapp, chat...) so
they can pull the up-to-date customer list without duplicating data.