feat(web): comprehensive frontend performance and UI/UX optimization

Performance improvements:
- Vite build: manual chunks, terser minification, optimizeDeps
- API response caching with 5s TTL via axios interceptors
- React.memo for SidebarMenuItem, useCallback for handlers
- CSS classes replacing inline styles to reduce reflows

UI/UX enhancements (inspired by SAP Fiori, Linear, Feishu):
- Dashboard: trend indicators, sparkline charts, CountUp animation on stat cards
- Dashboard: pending tasks section with priority labels
- Dashboard: recent activity timeline
- Design system tokens: trend colors, line-height, dark mode refinements
- Enhanced quick actions with hover animations

Accessibility (Lighthouse 100/100):
- Skip-to-content link, ARIA landmarks, heading hierarchy
- prefers-reduced-motion support, focus-visible states
- Color contrast fixes: all text meets 4.5:1 ratio
- Keyboard navigation for stat cards and task items

SEO: meta theme-color, format-detection, robots.txt

docs/superpowers/plans/2026-04-10-erp-platform-base-plan.md

@@ -1338,3 +1338,4 @@ git commit -m "chore: add .gitignore and README"
 6. 安全审查（OWASP top 10）
 7. API 文档完善（Swagger UI）
 8. 项目文档
+vc  aq