5f8726ee4e
17 domain design docs covering architecture, accounts, inventory, rentals, lessons, repairs, POS, payments, batch repairs, delivery, billing, accounting, deployment, licensing, installer, and backend tech architecture. Plus implementation roadmap (doc 18) and personnel management (doc 19). Key design decisions documented: - company/location model (multi-tenant + multi-location) - member entity (renamed from student to support multiple adults) - Stripe vs Global Payments billing ownership differences - User/location/terminal licensing model - Valkey 8 instead of Redis