Function spawn_transcript_lifecycle_sweep_loop 

pub fn spawn_transcript_lifecycle_sweep_loop(
    state: Db,
    cfg: TranscriptsConfig,
    interval: Duration,
) -> JoinHandle<()>

v0.7.0 I3 — spawn the periodic transcript archive→prune sweeper.

Sleeps interval, then calls crate::transcripts::sweep_transcript_lifecycle against the daemon’s shared connection. The per-namespace TTL configuration is captured by cfg once at spawn time (operators editing [transcripts] in config.toml after boot must restart the daemon — same model as the K2 pending sweeper).

The returned JoinHandle is owned by the caller; serve() aborts it on shutdown — same lifecycle as spawn_pending_timeout_sweep_loop.