Update latest lead timestamp for weekend S2L tracking

Weekend S2L form submissions lack a timestamp, leaving reps unsure which leads need urgent outreach. Records the latest submission time so sales ops can act same day.

Overview

Weekend Speed-to-Lead submissions often arrive without a clear timestamp, which leaves reps guessing and slows outreach. Record the latest submission time (with a short delay fallback) so sales ops can verify and prioritize same-day outreach.