reset_session() creates a fresh SessionEntry with created_at == updated_at,
but get_or_create_session() bumps updated_at on the next inbound message,
causing _is_new_session in _handle_message_with_agent to evaluate False.
The topic/channel skill auto-load gate (group_topics, channel_skill_bindings)
silently skips the first message after a manual reset.
Add an is_fresh_reset flag on SessionEntry, set by reset_session() and
consumed once by the message handler. Kept distinct from was_auto_reset
because that flag also drives a 'session expired due to inactivity'
user-facing notice and a context-note prepend — both wrong for an
explicit /new or /reset.
Persisted through to_dict/from_dict so the flag survives gateway
restart between /reset and the next message.
Fixes#6508
Co-authored-by: warabe1122 <45554392+warabe1122@users.noreply.github.com>
Co-authored-by: willy-scr <187001140+willy-scr@users.noreply.github.com>
fa9fd26acb