feat: add taste-design skill

[Leonxlnx]

Adds a new taste-design skill focused on generating opinionated DESIGN.md files that prevent generic AI outputs.

What it does:

• Configurable creativity dials (1-10 scale for density, variance, motion, creativity)
• Hero section rules with inline image typography
• 20+ explicitly banned anti-patterns (fake metrics, Inter font, neon purple, equal card grids, AI copywriting words, fabricated data)
• Typography guard with serif restrictions
• Mandatory responsive rules across 5 viewports
• Motion documented as code-phase intent (Stitch = static, motion = for coding agent)

Structure:
skills/taste-design/
SKILL.md
resources/DESIGN.md