The send path uses Hermes' reply-anchor fallback for DM topic lanes
(message_thread_id + reply_to_message_id), but send_chat_action only
accepts message_thread_id — Telegram's Bot API 10.0 rejects it for
these lanes. Without this short-circuit, every typing tick (~every 2s
during agent runs) makes a doomed API call that gets logged as a
'thread not found' debug warning. Skip the call entirely when the
metadata indicates a DM topic reply-fallback lane; the user-visible
behavior is unchanged (no typing indicator either way for these
lanes), but the logs stay clean.
Identified during salvage review of #22053.
aef297a45e