feat: Add advanced analytics UI components in frontend

- Add comprehensive API client methods for all advanced analytics endpoints
- Create CircadianRhythmCard component for sleep pattern visualization
- Create AnomalyAlertsPanel for anomaly detection and alerts
- Create GrowthPercentileChart with WHO/CDC percentiles
- Create CorrelationInsights for activity correlations
- Create TrendAnalysisChart with predictions
- Add advanced analytics page with all new components
- Add UI component library (shadcn/ui) setup
- Add navigation link to advanced analytics from insights page

All advanced analytics features are now accessible from the frontend UI.

maternal-web/lib/utils.ts

@@ -0,0 +1,6 @@
+import { type ClassValue, clsx } from "clsx"
+import { twMerge } from "tailwind-merge"
+
+export function cn(...inputs: ClassValue[]) {
+  return twMerge(clsx(inputs))
+}