add-backend

Everything about the data layer — pick one of six ready-to-run backend templates (TanStack Start + Drizzle + better-auth, Hono + Drizzle + better-auth, Hono + Prisma + better-auth, Hono + Drizzle + Auth.js/NextAuth, FastAPI + SQLAlchemy + JWT, Supabase) and wire the frontend to it through the Repository + AuthProvider seams; scaffold a CRUD resource (Postgres table + server fns + query hooks + DataTable page +…