docs: Add comprehensive multi-child implementation plan

Added detailed implementation plan covering:
- Frontend: Dynamic UI, child selector, bulk activity logging, comparison analytics
- Backend: Bulk operations, multi-child queries, family statistics
- AI/Voice: Child name detection, context building, clarification flows
- Database: Schema enhancements, user preferences, bulk operation tracking
- State management, API enhancements, real-time sync updates
- Testing strategy: Unit, integration, and E2E tests
- Migration plan with feature flags for phased rollout
- Performance optimizations: Caching, indexes, code splitting

Also includes:
- Security fixes for multi-family data leakage in analytics pages
- ParentFlow branding updates
- Activity tracking navigation improvements
- Backend DTO and error handling fixes

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

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

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

@@ -19,10 +19,11 @@ import { TabBar } from '../TabBar/TabBar';
 import { useMediaQuery } from '@/hooks/useMediaQuery';
 import { ReactNode } from 'react';
 import { useWebSocket } from '@/hooks/useWebSocket';
-import { Wifi, WifiOff, People, AccountCircle, Settings, ChildCare, Group, Logout, Gavel } from '@mui/icons-material';
+import { Wifi, WifiOff, People, AccountCircle, Settings, ChildCare, Group, Logout, Gavel, Favorite } from '@mui/icons-material';
 import { useTranslation } from '@/hooks/useTranslation';
 import { useRouter } from 'next/navigation';
 import { useAuth } from '@/lib/auth/AuthContext';
+import Link from 'next/link';
 
 interface AppShellProps {
   children: ReactNode;
@@ -93,7 +94,7 @@ export const AppShell = ({ children }: AppShellProps) => {
         }}
       >
         {/* Left Side - Family Members Online Indicator */}
-        <Box>
+        <Box sx={{ width: 80, display: 'flex', justifyContent: 'flex-start' }}>
           {isConnected && presence.count > 1 && (
             <Tooltip title={t('connection.familyMembersOnline', { count: presence.count })}>
               <Chip
@@ -109,7 +110,47 @@ export const AppShell = ({ children }: AppShellProps) => {
           )}
         </Box>
 
+        {/* Center - Logo */}
+        <Box
+          component={Link}
+          href="/"
+          sx={{
+            display: 'flex',
+            alignItems: 'center',
+            gap: 1,
+            textDecoration: 'none',
+            '&:hover': {
+              opacity: 0.8,
+            },
+            cursor: 'pointer',
+          }}
+        >
+          <Box
+            component="img"
+            src="/icon-192x192.png"
+            alt="ParentFlow logo"
+            sx={{
+              width: 32,
+              height: 32,
+              borderRadius: 1,
+            }}
+          />
+          <Box
+            component="span"
+            sx={{
+              fontWeight: 700,
+              fontSize: { xs: '0.95rem', sm: '1.1rem' },
+              background: (theme) => `linear-gradient(135deg, ${theme.palette.primary.main} 0%, ${theme.palette.secondary.main} 100%)`,
+              WebkitBackgroundClip: 'text',
+              WebkitTextFillColor: 'transparent',
+            }}
+          >
+            ParentFlow
+          </Box>
+        </Box>
+
         {/* Right Side - User Menu Button with Status Indicator */}
+        <Box sx={{ width: 80, display: 'flex', justifyContent: 'flex-end' }}>
         <Tooltip title={isConnected ? t('connection.syncActive') : t('connection.syncDisconnected')}>
           <IconButton
             onClick={handleMenuOpen}
@@ -207,6 +248,7 @@ export const AppShell = ({ children }: AppShellProps) => {
             <ListItemText>{t('navigation.logout')}</ListItemText>
           </MenuItem>
         </Menu>
+        </Box>
       </Box>
 
       <Container