Function set_next_poll 

pub async fn set_next_poll(
    pool: &SqlitePool,
    url: &str,
    delay: Duration,
) -> Result<()>

Schedule a feed’s next poll delay from now.

Lived as a private fn in the scheduler until web::add_subscription needed it too: a poll taken off the scheduler settled the error columns but never rescheduled, so a re-subscribed working feed stayed parked on its stale backoff horizon for up to 24h. One implementation, two callers.

upsert_feed COALESCEs unset fields, so supplying only url + next_poll bumps the schedule without clobbering title/validators/last_polled.