Addresses the missing-test and Content-Type points from the latest
PR #741 review:
- client/talk.py _talk_headers(): drop the manual `Content-Type:
application/json`. httpx sets it automatically on requests that pass
`json=`, and we no longer leak it onto bodyless GETs and DELETEs.
- tests/client/talk/test_talk_api.py:
- new `test_talk_list_participants_with_include_status` asserting
`includeStatus=true` is forwarded.
- new `test_talk_get_messages_invalid_last_given_header` covering
the defensive try/except around the `X-Chat-Last-Given` parse —
asserts the fallback `last_given=None` and that a warning is
logged.
- existing `test_talk_list_participants` extended to assert that
`includeStatus` is *absent* by default.
Unit tests: 13 → 15. Integration tests still 7/7.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
