Full-Stack Developer (React + Node) for SaaS Platform MVP

We're launching a SaaS platform for independent fitness coaches to manage clients, programs, and payments, and need a strong full-stack developer to build the MVP. Frontend is React with TypeScript, backend is Node (open to NestJS), Postgres for data. We have wireframes and a clear feature list. We want clean, maintainable code, not a throwaway prototype. Scope: — Coach and client dashboards — Program builder (create and assign workout and nutrition plans) — Stripe subscription billing and client payments — Auth with role-based access (coach vs client) — REST API and a Postgres schema you'll help design Small team, so we need someone who makes sound architecture calls and moves fast without cutting corners on data integrity. Please answer: — A SaaS MVP you built end to end, and one architecture decision you'd defend — How you'd structure Stripe subscriptions so we can add tiers later without a rewrite