Returns all permitted comments on a support request. Customers and
service-account callers receive only public comments; private comment
bodies and attachments are excluded. Callers authenticated with DoiT
employee privileges receive both public and private comments, subject
to existing ticket authorization. Each comment includes public,
sourced from Zendesk: true means public and false means private
(internal). Missing visibility in legacy responses or snapshots means
unknown, not private. All comments are returned in a single response
(no pagination).