dto-design

Use immediately when user mentions: "DTO", "スキーマ", "schema", "データモデル", "data model", "Pydantic", "validation", "バリデーション", "型定義", "type definition", "data structure", "レコード", "record". MUST USE this skill for: - Designing Pydantic DTOs with field validation - Creating type-safe data structures - Implementing validators and model configurations - Any work in src/schemas/ directory