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/features/analytics/InsightsDashboard.tsx

@@ -44,6 +44,7 @@ import { useLocalizedDate } from '@/hooks/useLocalizedDate';
 import { useTranslation } from '@/hooks/useTranslation';
 import { useFormatting } from '@/hooks/useFormatting';
 import { BarChart, Bar, LineChart, Line, PieChart, Pie, Cell, XAxis, YAxis, CartesianGrid, Tooltip, Legend, ResponsiveContainer } from 'recharts';
+import { useAuth } from '@/lib/auth/AuthContext';
 
 type DateRange = '7days' | '30days' | '3months';
 
@@ -100,6 +101,7 @@ const getActivityColor = (type: ActivityType) => {
 
 export const InsightsDashboard: React.FC = () => {
   const router = useRouter();
+  const { user } = useAuth();
   const { format, formatDistanceToNow } = useLocalizedDate();
   const { t } = useTranslation('insights');
   const { formatNumber } = useFormatting();
@@ -110,30 +112,55 @@ export const InsightsDashboard: React.FC = () => {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
 
+  const familyId = user?.families?.[0]?.familyId;
+
   // Fetch children on mount
   useEffect(() => {
     const fetchChildren = async () => {
+      if (!familyId) {
+        setError('No family found');
+        return;
+      }
+
       try {
-        const childrenData = await childrenApi.getChildren();
+        console.log('[InsightsDashboard] Loading children for familyId:', familyId);
+        const childrenData = await childrenApi.getChildren(familyId);
+        console.log('[InsightsDashboard] Loaded children:', childrenData);
         setChildren(childrenData);
+
         if (childrenData.length > 0) {
-          setSelectedChild(childrenData[0].id);
+          // Validate selected child or pick first one
+          const validChild = childrenData.find(c => c.id === selectedChild);
+          if (!validChild) {
+            setSelectedChild(childrenData[0].id);
+          }
         }
       } catch (err: any) {
+        console.error('[InsightsDashboard] Failed to load children:', err);
         setError(err.response?.data?.message || t('errors.loadChildren'));
       }
     };
     fetchChildren();
-  }, []);
+  }, [familyId]);
 
   // Fetch activities when child or date range changes
   useEffect(() => {
-    if (!selectedChild) return;
+    if (!selectedChild || children.length === 0) return;
+
+    // Validate that selectedChild belongs to current user's children
+    const childExists = children.some(child => child.id === selectedChild);
+    if (!childExists) {
+      console.warn('[InsightsDashboard] Selected child not found in user\'s children, resetting');
+      setSelectedChild(children[0].id);
+      setError('Selected child not found. Showing data for your first child.');
+      return;
+    }
 
     const fetchActivities = async () => {
       setLoading(true);
       setError(null);
       try {
+        console.log('[InsightsDashboard] Fetching activities for child:', selectedChild);
         const days = dateRange === '7days' ? 7 : dateRange === '30days' ? 30 : 90;
         const endDate = endOfDay(new Date());
         const startDate = startOfDay(subDays(new Date(), days - 1));
@@ -144,8 +171,10 @@ export const InsightsDashboard: React.FC = () => {
           startDate.toISOString(),
           endDate.toISOString()
         );
+        console.log('[InsightsDashboard] Fetched activities:', activitiesData.length);
         setActivities(activitiesData);
       } catch (err: any) {
+        console.error('[InsightsDashboard] Failed to load activities:', err);
         setError(err.response?.data?.message || t('errors.loadActivities'));
       } finally {
         setLoading(false);
@@ -153,7 +182,7 @@ export const InsightsDashboard: React.FC = () => {
     };
 
     fetchActivities();
-  }, [selectedChild, dateRange]);
+  }, [selectedChild, dateRange, children]);
 
   // Calculate statistics
   const calculateStats = () => {