Lift trial-to-paid with a DB-triggered flow.

Three days before trial_ends_at, fire a recovery sequence: email reminder, WhatsApp nudge, final offer. Stops the moment upgraded_at is filled.

• Trigger: trial_ends_at − 3 days
• Channel: Email + WhatsApp escalation
• Goal: upgraded_at filled (or subscription_status = active)
• Variations: discount on day 2, founder note on day 3