Function parseTraceLine

Returns
    | {
        agentId: string;
        amc_trace_v: 1;
        event: | "tool_result"
        | "llm_call"
        | "llm_result"
        | "tool_intent"
        | "verification_step";
        hashes?: { input_sha256?: string; output_sha256?: string };
        model?: string;
        note?: string;
        providerId?: string;
        receipt?: string;
        request_id?: string;
        ts: number;
    }
    | null