feat: Redesign mobile UI with centered voice button and user menu

- Repositioned Voice Command button to center of bottom navigation bar
- Added floating user menu icon in top-left corner on mobile
- User menu includes: Settings, Children, Family, and Logout options
- Updated bottom nav to show: Home, Track, Voice (center), Insights, History
- Hide original floating voice button on mobile to avoid duplication
- Improved mobile UX with easier thumb access to voice commands
- User avatar displays first letter of user's name

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

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

maternal-web/components/layouts/AppShell/AppShell.tsx

@@ -1,13 +1,28 @@
 'use client';
 
-import { Box, Container, Chip, Tooltip } from '@mui/material';
+import { useState } from 'react';
+import {
+  Box,
+  Container,
+  Chip,
+  Tooltip,
+  IconButton,
+  Menu,
+  MenuItem,
+  ListItemIcon,
+  ListItemText,
+  Avatar,
+  Divider,
+} from '@mui/material';
 import { MobileNav } from '../MobileNav/MobileNav';
 import { TabBar } from '../TabBar/TabBar';
 import { useMediaQuery } from '@/hooks/useMediaQuery';
 import { ReactNode } from 'react';
 import { useWebSocket } from '@/hooks/useWebSocket';
-import { Wifi, WifiOff, People } from '@mui/icons-material';
+import { Wifi, WifiOff, People, AccountCircle, Settings, ChildCare, Group, Logout } from '@mui/icons-material';
 import { useTranslation } from '@/hooks/useTranslation';
+import { useRouter } from 'next/navigation';
+import { useAuth } from '@/lib/auth/AuthContext';
 
 interface AppShellProps {
   children: ReactNode;
@@ -15,9 +30,31 @@ interface AppShellProps {
 
 export const AppShell = ({ children }: AppShellProps) => {
   const { t } = useTranslation('common');
+  const router = useRouter();
+  const { user, logout } = useAuth();
   const isMobile = useMediaQuery('(max-width: 768px)');
   const isTablet = useMediaQuery('(max-width: 1024px)');
   const { isConnected, presence } = useWebSocket();
+  const [anchorEl, setAnchorEl] = useState<null | HTMLElement>(null);
+
+  const handleMenuOpen = (event: React.MouseEvent<HTMLElement>) => {
+    setAnchorEl(event.currentTarget);
+  };
+
+  const handleMenuClose = () => {
+    setAnchorEl(null);
+  };
+
+  const handleNavigate = (path: string) => {
+    handleMenuClose();
+    router.push(path);
+  };
+
+  const handleLogout = async () => {
+    handleMenuClose();
+    await logout();
+    router.push('/login');
+  };
 
   return (
     <Box sx={{
@@ -29,6 +66,85 @@ export const AppShell = ({ children }: AppShellProps) => {
     }}>
       {!isMobile && <MobileNav />}
 
+      {/* Mobile User Menu Button - Top Left */}
+      {isMobile && (
+        <Box
+          sx={{
+            position: 'fixed',
+            top: 8,
+            left: 8,
+            zIndex: 1200,
+          }}
+        >
+          <IconButton
+            onClick={handleMenuOpen}
+            size="small"
+            aria-label="user menu"
+            aria-controls={anchorEl ? 'user-menu' : undefined}
+            aria-haspopup="true"
+            aria-expanded={anchorEl ? 'true' : undefined}
+            sx={{
+              bgcolor: 'background.paper',
+              boxShadow: 1,
+              '&:hover': {
+                bgcolor: 'background.paper',
+                boxShadow: 2,
+              },
+            }}
+          >
+            <Avatar
+              sx={{
+                width: 32,
+                height: 32,
+                bgcolor: 'primary.main',
+                fontSize: '0.875rem',
+              }}
+            >
+              {user?.name?.charAt(0).toUpperCase() || 'U'}
+            </Avatar>
+          </IconButton>
+
+          <Menu
+            id="user-menu"
+            anchorEl={anchorEl}
+            open={Boolean(anchorEl)}
+            onClose={handleMenuClose}
+            onClick={handleMenuClose}
+            transformOrigin={{ horizontal: 'left', vertical: 'top' }}
+            anchorOrigin={{ horizontal: 'left', vertical: 'bottom' }}
+            sx={{
+              mt: 1,
+            }}
+          >
+            <MenuItem onClick={() => handleNavigate('/settings')}>
+              <ListItemIcon>
+                <Settings fontSize="small" />
+              </ListItemIcon>
+              <ListItemText>{t('navigation.settings')}</ListItemText>
+            </MenuItem>
+            <MenuItem onClick={() => handleNavigate('/children')}>
+              <ListItemIcon>
+                <ChildCare fontSize="small" />
+              </ListItemIcon>
+              <ListItemText>{t('navigation.children')}</ListItemText>
+            </MenuItem>
+            <MenuItem onClick={() => handleNavigate('/family')}>
+              <ListItemIcon>
+                <Group fontSize="small" />
+              </ListItemIcon>
+              <ListItemText>{t('navigation.family')}</ListItemText>
+            </MenuItem>
+            <Divider />
+            <MenuItem onClick={handleLogout}>
+              <ListItemIcon>
+                <Logout fontSize="small" color="error" />
+              </ListItemIcon>
+              <ListItemText>{t('navigation.logout')}</ListItemText>
+            </MenuItem>
+          </Menu>
+        </Box>
+      )}
+
       {/* Connection Status & Presence Indicator */}
       <Box
         sx={{