Spec 6.2 says: 'Default JSON response wraps the same data in a
{items, total, returned, has_more} envelope so the frontend can
paginate uniformly.' Previously the GET list endpoints defaulted
to NDJSON (consistent with the parse endpoints), which forced
every curl call to set Accept: application/json.
Now NDJSON is strictly opt-in via Accept: application/x-ndjson;
JSON is the default. Parse endpoints keep their existing NDJSON
default (browser uploads).
T8 test 'test_claims_default_accept_returns_ndjson' updated to
assert the new default.
Tyler