Type error with `"declaration": true`

[BryceRussell]

If someone authors a theme inside a monorepo with a tsconfig.json that includes "declaration": true, the defineTheme function shows a type error

The inferred type of 'default' cannot be named without a reference to './node_modules/astro-theme-provider/dist/internal/types.js'. This is likely not portable. A type annotation is necessary.

Related issue: microsoft/TypeScript#47663

Workaround: re-export AuthorOptions and UserOptions

need example