Extends record_turn_memory_for_present with a you_present: bool = True
kwarg so a single entry-point covers both you-scenes (witness_you=1)
and meanwhile scenes (witness_you=0). Validates that meanwhile callers
provide a guest_bot_id.
record_meanwhile_memory becomes a thin backward-compat wrapper that
delegates with you_present=False, preserving the call site in
chat/web/meanwhile.py without churn.
Joseph Doherty