backend-dev-guidelines

Comprehensive backend development guide for Supabase Edge Functions + PostgreSQL. Use when working with Supabase (database, auth, storage, realtime), Edge Functions, PostgreSQL, Row-Level Security (RLS), Resend email, Stripe payments, or TypeScript backend patterns. Covers database design, auth flows, Edge Function patterns, RLS policies, email integration, payment processing, and deployment to Supabase.