Integrate impeccable design skills into AI command

[youknowriad]

Related issues

• Related to https://github.com/pbakaus/impeccable

How AI was used in this PR

Claude Code explored the impeccable repo structure, identified integration options, and implemented the chosen approach. All changes were reviewed.

Proposed Changes

• Add impeccable as a GitHub npm dependency for its comprehensive design skill system (1 frontend-design skill with 7 reference files + 20 command skills)
• Register impeccable as a second local plugin in the Claude Agent SDK, loaded alongside our existing Studio plugin at build time via vite-plugin-static-copy
• Replace the inline LOCAL_DESIGN_GUIDELINES in the system prompt with a reference to impeccable's frontend-design skill, keeping WordPress-specific block constraints
• Add all 20 impeccable slash commands (/polish, /animate, /audit, /typeset, /overdrive, etc.) to the autocomplete registry

Testing Instructions

• Run npm install && npm run cli:build
• Verify skills appear in dist: ls apps/cli/dist/cli/plugins/impeccable/.claude/skills/
• Run node apps/cli/dist/cli/main.mjs ai and confirm impeccable slash commands appear in autocomplete
• Test /polish or /animate on a local WordPress site to verify the skills invoke correctly

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?