getMaybeString

Read a Maybe<Opaque<String>> field as nullable String:

• null when the option's is_some == false (i.e. the contract holds None).

• the decoded UTF-8 string otherwise.

The compact runtime marshals Maybe<T> as a struct {is_some: Boolean, value: T}; this accessor unwraps the shape so callers don't have to know the struct layout. Use getMaybeStringOrNull when the schema may have evolved and the field might be missing entirely.