Interface SynthesisChunk

One source chunk for synthesis: its id, conversation, reassembled text, and the metadata the footnote line needs. Text is NOT stored — the caller pulls it from store.chunkText(id).

interface SynthesisChunk {
    conv: string;
    dateMs: number | null;
    id: string;
    label: string | null;
    text: string;
    title: string;
}