Normalize a `fontFamilies` prop (mix of strings and FontOption objects) into a uniform `FontOption[]`. Returns `undefined` for `undefined` input so callers fall back to their built-in defaults. Strings expand into the `'other'` group with no CSS fallback chain.

declare function normalizeFontFamilies(fontFamilies: ReadonlyArray<string | FontOption> | undefined): FontOption[] | undefined;

Shared FontOption shape + normaliser used by FontPicker components in both adapters. Lifted from packages/react/src/components/ui/ normalizeFontFamilies.ts so the type definition has a single home.

interface FontOption