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/layouts/MobileNav/MobileNav.tsx

@@ -0,0 +1,114 @@
+'use client';
+
+import { useState } from 'react';
+import { useRouter } from 'next/navigation';
+import {
+  AppBar,
+  Toolbar,
+  IconButton,
+  Typography,
+  Drawer,
+  List,
+  ListItem,
+  ListItemButton,
+  ListItemIcon,
+  ListItemText,
+  Avatar,
+  Box,
+  Divider,
+} from '@mui/material';
+import {
+  Menu as MenuIcon,
+  Home,
+  Timeline,
+  Chat,
+  Insights,
+  Settings,
+  ChildCare,
+  Group,
+  Logout,
+} from '@mui/icons-material';
+
+export const MobileNav = () => {
+  const [drawerOpen, setDrawerOpen] = useState(false);
+  const router = useRouter();
+
+  const menuItems = [
+    { label: 'Dashboard', icon: <Home />, path: '/' },
+    { label: 'Track Activity', icon: <Timeline />, path: '/track' },
+    { label: 'AI Assistant', icon: <Chat />, path: '/ai-assistant' },
+    { label: 'Insights', icon: <Insights />, path: '/insights' },
+    { label: 'Children', icon: <ChildCare />, path: '/children' },
+    { label: 'Family', icon: <Group />, path: '/family' },
+    { label: 'Settings', icon: <Settings />, path: '/settings' },
+  ];
+
+  const handleNavigate = (path: string) => {
+    router.push(path);
+    setDrawerOpen(false);
+  };
+
+  return (
+    <>
+      <AppBar position="static" elevation={1} sx={{ bgcolor: 'background.paper' }}>
+        <Toolbar>
+          <IconButton
+            edge="start"
+            color="primary"
+            aria-label="menu"
+            onClick={() => setDrawerOpen(true)}
+          >
+            <MenuIcon />
+          </IconButton>
+          <Typography variant="h6" component="div" sx={{ flexGrow: 1, color: 'primary.main', fontWeight: 600 }}>
+            Maternal
+          </Typography>
+          <Avatar sx={{ bgcolor: 'primary.main' }}>U</Avatar>
+        </Toolbar>
+      </AppBar>
+
+      <Drawer
+        anchor="left"
+        open={drawerOpen}
+        onClose={() => setDrawerOpen(false)}
+      >
+        <Box
+          sx={{ width: 280 }}
+          role="presentation"
+        >
+          <Box sx={{ p: 3, bgcolor: 'primary.light' }}>
+            <Avatar sx={{ width: 64, height: 64, bgcolor: 'primary.main', mb: 2 }}>U</Avatar>
+            <Typography variant="h6" fontWeight="600">User Name</Typography>
+            <Typography variant="body2" color="text.secondary">user@example.com</Typography>
+          </Box>
+
+          <List>
+            {menuItems.map((item) => (
+              <ListItem key={item.path} disablePadding>
+                <ListItemButton onClick={() => handleNavigate(item.path)}>
+                  <ListItemIcon sx={{ color: 'primary.main' }}>
+                    {item.icon}
+                  </ListItemIcon>
+                  <ListItemText primary={item.label} />
+                </ListItemButton>
+              </ListItem>
+            ))}
+          </List>
+
+          <Divider sx={{ my: 1 }} />
+
+          <List>
+            <ListItem disablePadding>
+              <ListItemButton onClick={() => handleNavigate('/logout')}>
+                <ListItemIcon sx={{ color: 'error.main' }}>
+                  <Logout />
+                </ListItemIcon>
+                <ListItemText primary="Logout" />
+              </ListItemButton>
+            </ListItem>
+          </List>
+        </Box>
+      </Drawer>
+    </>
+  );
+};