Agent Skills: principles

Provides development principles, guidelines, and VibeCoder guidance. Use when user mentions 原則, principles, ガイドライン, guidelines, VibeCoder, 安全性, safety, 差分編集, diff-aware. Triggers: 原則, principles, ガイドライン, VibeCoder, 安全性, 差分編集. Do not use for actual implementation - use impl skill instead.