Extract Dungeons & Dragons combat-turn artifacts from the supplied transcript.

Include a record only when the transcript establishes that an in-world
participant takes a combat turn or performs a discrete interrupting combat
event. Interrupting events belong at the point where they occur in transcript
chronology.

Exclude initiative setup without a turn or combat event, tactical planning,
table talk, rules lookup, hypothetical events, abandoned intentions, recaps
outside the current passage, and downstream consequences.

Do not infer combat events from D&D rules knowledge. Preserve the session as
played and attribute relevant nonstandard rulings to the GM or table.

Unmatched actors remain permitted.

Place all supporting transcript ranges for a turn in its turn-level source_refs
collection.
