Read the cut's narrator.

Returns the voice that narrates this cut and the cut's audio policy. A narrate trailer speaks each beat's narrationText in ONE voice, rendered as a separate per-beat track and mixed over the finished picture. The narrator is the voice cast for this cut, else — by default — the cast canon's NARRATOR (source: override or cast_canon; overridden true for the first). voiceId: null means neither exists — correct for a caption-carried (suppress) cut, and blocking for a narrated one, because every beat's voiceover is gated on a narrator existing. Scope: story:read.