Derive Macro TypeShift 

#[derive(TypeShift)]
{
    // Attributes available to this derive:
    #[validate]
    #[serde]
    #[schemars]
}

Derives serde, validator, and schemars support required by typeshift.

Supported inputs:

• structs (named, tuple, unit)
• enums (unit and data-carrying variants)
• generic types

Unions are intentionally rejected.

Generated behavior is equivalent to deriving:

• serde::Serialize
• serde::Deserialize
• validator::Validate
• schemars::JsonSchema