* fix(transcript): recognize agent row ids in replay merge
* Strip imported _row_id so replay merge cannot trust caller provenance.
Session import already dropped _state_db_row_id aliases. After treating
Agent _row_id as identity, the same public/import scrubber must drop that
field too, or a crafted import can collide with a later state.db turn.
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Co-authored-by: Anthony Ruiz <ruizanthony@users.noreply.github.com>
Co-authored-by: nesquena-hermes <nesquena+hermes@gmail.com>