Add Phase 2 & 3: Web frontend with authentication and tracking features

- Initialize Next.js 14 web application with Material UI and TypeScript
- Implement authentication (login/register) with device fingerprint
- Create mobile-first responsive layout with app shell pattern
- Add tracking pages for feeding, sleep, and diaper changes
- Implement activity history with filtering
- Configure backend CORS for web frontend (port 3030)
- Update backend port to 3020, frontend to 3030
- Fix API response handling for auth endpoints

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

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

maternal-web/components/ThemeRegistry.tsx

@@ -0,0 +1,21 @@
+'use client';
+
+import { ThemeProvider } from '@mui/material/styles';
+import CssBaseline from '@mui/material/CssBaseline';
+import { AppRouterCacheProvider } from '@mui/material-nextjs/v14-appRouter';
+import { maternalTheme } from '@/styles/themes/maternalTheme';
+import { AuthProvider } from '@/lib/auth/AuthContext';
+import { ReactNode } from 'react';
+
+export function ThemeRegistry({ children }: { children: ReactNode }) {
+  return (
+    <AppRouterCacheProvider>
+      <ThemeProvider theme={maternalTheme}>
+        <CssBaseline />
+        <AuthProvider>
+          {children}
+        </AuthProvider>
+      </ThemeProvider>
+    </AppRouterCacheProvider>
+  );
+}