Further refinements on top of #2795:
- persist real session_id (notify_session_id) at task creation so group chats
correctly map back to the user's actual conversation
- mark scheduler turns with [SCHEDULED] (recognise legacy "Scheduled task"
prefix too for backward-compatible pruning)
- prune both DB and in-memory to scheduler_inject_max_per_session (default 3),
only marker-tagged pairs are touched; regular user turns never deleted
- send_message type gated by scheduler_inject_send_message (default false) —
fixed reminder text rarely benefits follow-up Q&A
Co-authored-by: huangrichao2020 <grdomai43881@gmail.com>
