0.1.3 – security & correctness hardening

• freeze env object at runtime (Object.freeze)
• toJSON non-enumerable via Object.defineProperty
• deduplicate redactErrorMessage, export from validator
• buildZodSchema default branch throws on unknown FieldType
• .env parser: fix single-char quote edge case, add inline comment stripping
• nestjs: expose validated env as 'ENV' injection token
• remove dead CreateEnvOptions interface"