Implement Phase 7 Performance Optimization and fix tracking system

Phase 7 Implementation:
- Add lazy loading for AI Assistant and Insights pages
- Create LoadingFallback component with skeleton screens (page, card, list, chart, chat variants)
- Create OptimizedImage component with Next.js Image optimization
- Create PerformanceMonitor component with web-vitals v5 integration
- Add performance monitoring library tracking Core Web Vitals (CLS, INP, FCP, LCP, TTFB)
- Install web-vitals v5.1.0 dependency
- Extract AI chat interface and insights dashboard to lazy-loaded components

Tracking System Fixes:
- Fix API data transformation between frontend (timestamp/data) and backend (startedAt/metadata)
- Update createActivity, getActivities, and getActivity to properly transform data structures
- Fix diaper, feeding, and sleep tracking pages to work with backend API

Homepage Improvements:
- Connect Today's Summary to backend daily summary API
- Load real-time data for feeding count, sleep hours, and diaper count
- Add loading states and empty states for better UX
- Format sleep duration as "Xh Ym" for better readability
- Display child name in summary section

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

maternal-web/package-lock.json

@@ -28,6 +28,7 @@
         "recharts": "^3.2.1",
         "redux-persist": "^6.0.0",
         "socket.io-client": "^4.8.1",
+        "web-vitals": "^5.1.0",
         "workbox-webpack-plugin": "^7.3.0",
         "workbox-window": "^7.3.0",
         "zod": "^3.25.76"
@@ -12851,6 +12852,12 @@
         "node": ">=10.13.0"
       }
     },
+    "node_modules/web-vitals": {
+      "version": "5.1.0",
+      "resolved": "https://registry.npmjs.org/web-vitals/-/web-vitals-5.1.0.tgz",
+      "integrity": "sha512-ArI3kx5jI0atlTtmV0fWU3fjpLmq/nD3Zr1iFFlJLaqa5wLBkUSzINwBPySCX/8jRyjlmy1Volw1kz1g9XE4Jg==",
+      "license": "Apache-2.0"
+    },
     "node_modules/webidl-conversions": {
       "version": "4.0.2",
       "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-4.0.2.tgz",