Add skeleton loading states across all tracking pages

- Replace CircularProgress spinners with content-aware skeleton screens
- Add FormSkeleton for form loading states (feeding, sleep, diaper pages)
- Add ActivityListSkeleton for recent activities loading
- Improves perceived performance with layout-matching placeholders

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

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

maternal-web/app/analytics/page.tsx

@@ -18,6 +18,7 @@ import { AppShell } from '@/components/layouts/AppShell/AppShell';
 import { ProtectedRoute } from '@/components/common/ProtectedRoute';
 import { ErrorBoundary } from '@/components/common/ErrorBoundary';
 import { ChartErrorFallback } from '@/components/common/ErrorFallbacks';
+import { StatGridSkeleton, ChartSkeleton } from '@/components/common/LoadingSkeletons';
 import {
   TrendingUp,
   Hotel,
@@ -102,15 +103,14 @@ export default function AnalyticsPage() {
     return (
       <ProtectedRoute>
         <AppShell>
-          <Box
-            sx={{
-              display: 'flex',
-              justifyContent: 'center',
-              alignItems: 'center',
-              minHeight: '60vh',
-            }}
-          >
-            <CircularProgress />
+          <Box>
+            <Typography variant="h4" gutterBottom fontWeight="600" sx={{ mb: 3 }}>
+              Analytics & Insights
+            </Typography>
+            <StatGridSkeleton count={3} />
+            <Box sx={{ mt: 4 }}>
+              <ChartSkeleton height={350} />
+            </Box>
           </Box>
         </AppShell>
       </ProtectedRoute>