Ambient transcript watermarks now carry the transcript session id, resolve only for the current session entry, and skip stale room-event hooks that no longer match the prepared transcript session.
This protects Telegram group prompt windows after reset by backfilling rows that are no longer present in the new session transcript, while preserving steady-state watermark filtering within one session.
Fixes#99373
Release-note: fixes Telegram group context loss after session reset when ambient transcript watermarks outlived the transcript they referenced.