-- First-time deposit flag (set on first completed crypto deposit for user)
ALTER TABLE payments
    ADD COLUMN ftd TINYINT(1) NOT NULL DEFAULT 0 COMMENT 'First-time deposit (FTD)' AFTER completed_at;

-- Supports admin analytics: COUNT FTD payments per day by completion time
CREATE INDEX idx_payments_status_ftd_completed_at ON payments (status, ftd, completed_at);
