tanstack-start-server-only

TanStack Start server-only patterns using createServerOnlyFn and cloudflare:workers env access. Use when: accessing Cloudflare environment variables (APP_URL, STRIPE_SECRET_KEY, etc.), creating server-only utility functions, working with Stripe or other server-only APIs, or when you need to ensure code only runs on the server and throws if called from client. Covers createServerOnlyFn vs createServerFn differences, env access patterns, and centralized server-only utilities.