Variants System

Two forms:

1. Object-based (variants.pure/input/result) – enable flags + suffix + excludeFields.
2. Array-based custom variants – each element: { name, suffix?, exclude?, additionalValidation?, makeOptional?, transformRequiredToOptional?, transformOptionalToRequired?, removeValidation? }.

Generation behavior:

• Skips entirely if emit.variants=false or single-file mode active (variants suppressed in strict single-file).
• Pure models may still generate separately (emit.pureModels).
• pureVariantOnlyMode & pureModelsOnlyMode heuristics reduce other schema categories.

Custom variant field building applies:

• Base inferred zod type
• Optionality transforms
• Additional validations from variant def or @zod doc comments
• Enum imports resolved relative to variants directory