Bun Tanstack Start

This gets TanStack Start running with Bun instead of Node, which matters because TanStack Start is a full-stack React framework built on TanStack Router and it can be picky about runtimes. The skill covers the usual file-based routing, server functions with `createServerFn`, and API routes, plus it shows you how to set the Bun preset in `app.config.ts` so the SSR and build pipeline actually work. The server function examples use Bun's native SQLite, which is a nice touch. It also includes the security warnings about scaffolding tools executing remote code, which is realistic given that `bunx create-tanstack-start` pulls from npm. Reach for this when you hit preset or SSR errors, or when you just want Bun's speed for a router-heavy React app.