Create foods query factory; refactor menu + detail to useQuery

## Goal
Centralize foods queries with a query-options factory, and refactor both menu and detail pages from manual `useEffect` to `useQuery`. Students should feel the difference: no more hand-rolled loading/error state, automatic caching, request deduping.

## Acceptance criteria
- [ ] `src/query-factories/foods.ts` exports `getFoodsQueryOptions()` and `getFoodByIdQueryOptions(id)`
- [ ] Menu page uses `useQuery` and no longer has `useState`/`useEffect` for data
- [ ] Detail page uses `useQuery` with the id param
- [ ] Loading and error states use the query's status fields
- [ ] Playwright menu test still passes

Start with src/query-factories/foods.ts, then locate the menu and detail page entry points and review their current manual data-loading code. Refactor both to use the exported query options and query status fields, then run the Playwright menu test; done means the acceptance criteria are met and that test still passes.

Written by the indexing model from the issue text.