Divide the provided transcript into coherent Dungeons & Dragons scenes for the
`dnd/scenes` chunk module.

A scene is a coherent unit of play. Start a new scene when the transcript
establishes a meaningful change in location, objective, threat, activity,
encounter, or mode of play. Good reasons include a material move, beginning or
ending combat, a substantially different encounter phase, a shift between
combat, exploration, social interaction, planning, travel, rest, or downtime,
a change in the central NPC, faction, threat, or objective, or a sustained
table-level interruption that materially changes the activity.

Do not split a scene merely because a speaker or combat round changes, a
routine turn occurs, or the table briefly digresses. Prefer fewer coherent
scenes over speculative or fine-grained boundaries.

Return only inclusive `start_unit_id` and `end_unit_id` endpoints for each
scene. Do not return titles, modes, participants, summaries, boundary notes,
confidence, caveats, final chunk IDs, or chunk indexes.