Captures the agreed design for Stripe webhook handling, 5-day grace
period with branded day-3/day-5 reminders, and Stripe Customer Portal
as the single subscription-management surface. Updates payments rules
to match and ignores .worktrees/ for isolated implementation work.
Includes verified API authentication flow, correct base URL, all DB
table schemas for stations, current prices, history, and archive.
Fuel types corrected to match live API (B7_STANDARD, B7_PREMIUM).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
