버튼 시스템

6. 버튼 시스템 Create a comprehensive button component system: **Size Variants**: - xs: 28px height, 12px padding-x, 12px font - sm: 32px height, 14px padding-x, 13px font - md: 40px height, 20px padding-x, 14px font - lg: 48px height, 28px padding-x, 16px font - xl: 56px height, 36px padding-x, 18px font **Style Variants**: - Primary: Brand color fill, white text - Secondary: Gray-100 fill, gray-900 text - Outline: 2px border, transparent fill - Ghost: No border, hover background - Destructive: Red-600 fill for dangerous actions - Link: Underline style, inline display **States** (for each variant): - Default, Hover (+10% darker), Active (+15% darker) - Focus: 2px ring offset-2 brand color - Disabled: 50% opacity, cursor-not-allowed - Loading: Spinner icon replacing text, maintain width **Icon Support**: - Leading icon: 8px gap before text - Trailing icon: 8px gap after text - Icon-only: Square aspect ratio Tech: React + CVA (class-variance-authority) + Tailwind