Four targeted fixes from the AI code review:
1. TalkConversation.description: drop the misleading `str | None`
union (spreed always sends `""`, never null) — type is now `str`
with default `""`.
2. get_messages: guard the X-Chat-Last-Given int parse with
try/except so a misbehaving proxy can't crash the read flow;
logs a warning and falls back to None.
3. get_messages: clamp `limit` to [1, 200] in the client (spreed
caps server-side at 200 and silently truncates) so the returned
`count` always matches what was actually requested. Both client
and server-tool docstrings updated to state the valid range.
4. Add an integration test covering the 32000-char message ceiling
in talk_send_message — the empty-message case was already tested,
the over-length case was not.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
