Add backend with analytics, notifications, and enhanced features

Backend:
- Complete NestJS backend implementation with comprehensive features
- Analytics: Weekly/monthly reports with PDF/CSV export
- Smart notifications: Persistent notifications with milestones and anomaly detection
- AI safety: Medical disclaimer triggers and prompt injection protection
- COPPA/GDPR compliance: Full audit logging system

Frontend:
- Updated settings page and analytics components
- API integration improvements

Docs:
- Added implementation gaps tracking
- Azure OpenAI integration documentation
- Testing and post-launch summaries

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

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

maternal-web/lib/api/users.ts

@@ -1,7 +1,14 @@
 import apiClient from './client';
 
+export interface UserPreferences {
+  notifications?: boolean;
+  emailUpdates?: boolean;
+  darkMode?: boolean;
+}
+
 export interface UpdateProfileData {
   name?: string;
+  preferences?: UserPreferences;
 }
 
 export interface UserProfile {
@@ -11,6 +18,7 @@ export interface UserProfile {
   role: string;
   locale: string;
   emailVerified: boolean;
+  preferences?: UserPreferences;
   families?: string[];
 }