fix: UI polish details and add audit skill

[overtrue]

Pull Request

Description

Polishes UI details across auth and dashboard surfaces, covering spacing, alignment, density, accessibility labels, table/form/dialog details, theme handling, and icon sizing. Adds a reusable skills/ui-audit package so future UI walkthroughs can reuse the same inspection matrix. Also repairs the lockfile by removing an accidental extra YAML document so frozen installs can parse it.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Code refactoring
• Performance improvement
• Test improvements
• Security fix

Testing

• Unit tests added/updated
• Manual testing completed

CI=true pnpm install --frozen-lockfile
pnpm type-check
pnpm lint
pnpm format:check
git diff --check
python3 /Users/overtrue/.nvm/versions/node/v22.14.0/lib/node_modules/clawdbot/skills/skill-creator/scripts/quick_validate.py skills/ui-audit
node --test tests/lib/i18n-locales.test.js

Full direct node --test tests/lib/*.test.js tests/lib/*.test.ts is blocked by the repository's current test runner setup for TS imports and extension resolution. The direct i18n test passes after adding the missing locale keys.

Checklist

• Code follows the project's style guidelines
• Self-review completed
• TypeScript types are properly defined
• All commit messages are in English (Conventional Commits)
• All existing tests pass
• No new dependencies added, or they are justified

Related Issues

N/A

Screenshots (if applicable)

Screenshots were captured during the local UI walkthrough; no hosted screenshots are attached to this PR body.

Additional Notes

This PR includes the reusable UI audit skill under skills/ui-audit/.