Allow arbitrary custom keys with S.meta

[king-smith]

S.meta currently only supports name, title, description, deprecated & examples. I need to attach custom metadata (notably x-* keywords per JSON Schema custom annotations) and can’t express this in Sury, where I can in a few other libraries (Zod, ArkType, Valibot).

For now I can merge the annotations afterwards without too much hassle, but it’d be great to be able to define them directly with S.meta.

[DZakh]

I didn't know about this one. I'll add support for this in future versions.

[DZakh]

By the way, there is extendJSONSchema you can use.

export function extendJSONSchema<Output, Input>(
  schema: Schema<Output, Input>,
  jsonSchema: JSONSchema7
): Schema<Output, Input>;