feat: Document required + default as optional

[WoH]

Required + default does not make sense – if a value is required, the client must always send it, and the default value is never used.

For user convenience however, it makes sense in TypeScript to declare non-optional + default, since the validation layer fills defaults on required properties.

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Potential Problems With The Approach

Should be considered breaking. Even though it should only reflect the actual behavior of the validation more accurately.