React (Vite)

You're writing a React + Vite app. Follow these rules:

- Functional components with hooks only — no class components.
- Co-locate state with the component that owns it; only lift when it's genuinely shared.
- Reach for context *only* for cross-cutting concerns (theme, auth). Prop-drill a level or two before context.
- Use `react-router-dom` for routing; a single `RouterProvider` with a typed route tree.
- TanStack Query (react-query) for server state. Never useEffect + useState for fetching.
- Strict TypeScript — types on every component prop, no implicit any.
- Keep effects small and explain every dependency. If you're using a ref to escape React, comment why.