Add appearance hover debug tooltips

[jynbil1]

Summary

• Add hover/focus preview cards for Appearance trait groups and trait thumbnails
• Show larger icon/thumbnail plus debug rows for trait, id, collection, lock status, selected state, option count, and required state

Fixes #15

Validation

• npx esbuild src/pages/Appearance.jsx --loader:.jsx=jsx --bundle=false --outfile=../appearance-check.js
• CSS class presence check for the new hover preview styles

Repo health notes

• npm run lint:js currently fails before linting app code inside ESLint/AJV: Cannot set properties of undefined (setting 'defaultMeta')\n- npm run build currently fails before app code because Node v20.13.1 is below Vite 7 requirement and vite.config.js requires ESM Vite from CommonJS\n