feat(compliance): Implement COPPA/GDPR compliance UI

Frontend Compliance Features:
- Created compliance API client (data export, account deletion, deletion status)
- Added DataExport component with download functionality
- Added AccountDeletion component with 30-day grace period UI
- Updated Settings page with Privacy & Compliance sections

COPPA Age Verification:
- Added date of birth field to registration
- Age calculation with COPPA compliance (under 13 blocked)
- Parental email and consent for users 13-17
- Dynamic form validation based on age

Privacy & Terms:
- Separate checkboxes for Terms of Service and Privacy Policy
- Required acceptance for registration
- Links to policy pages

Completes GDPR Right to Data Portability and Right to Erasure.
Completes COPPA parental consent requirements.

maternal-web/components/settings/DataExport.tsx

@@ -0,0 +1,71 @@
+'use client';
+
+import { useState } from 'react';
+import {
+  Card,
+  CardContent,
+  Typography,
+  Button,
+  Box,
+  CircularProgress,
+  Alert,
+} from '@mui/material';
+import { Download } from '@mui/icons-material';
+import { complianceApi } from '@/lib/api/compliance';
+
+export function DataExport() {
+  const [isExporting, setIsExporting] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [success, setSuccess] = useState<string | null>(null);
+
+  const handleExport = async () => {
+    setIsExporting(true);
+    setError(null);
+    setSuccess(null);
+
+    try {
+      await complianceApi.downloadUserData();
+      setSuccess('Your data has been downloaded successfully!');
+    } catch (err: any) {
+      console.error('Failed to export data:', err);
+      setError(err.response?.data?.message || 'Failed to export data. Please try again.');
+    } finally {
+      setIsExporting(false);
+    }
+  };
+
+  return (
+    <Card>
+      <CardContent>
+        <Typography variant="h6" fontWeight="600" gutterBottom>
+          Data Export
+        </Typography>
+        <Typography variant="body2" color="text.secondary" sx={{ mb: 2 }}>
+          Download all your data in JSON format. This includes your profile, children, activities, and AI conversations.
+          This complies with GDPR's Right to Data Portability.
+        </Typography>
+
+        {error && (
+          <Alert severity="error" sx={{ mb: 2 }} onClose={() => setError(null)}>
+            {error}
+          </Alert>
+        )}
+
+        {success && (
+          <Alert severity="success" sx={{ mb: 2 }} onClose={() => setSuccess(null)}>
+            {success}
+          </Alert>
+        )}
+
+        <Button
+          variant="outlined"
+          startIcon={isExporting ? <CircularProgress size={20} /> : <Download />}
+          onClick={handleExport}
+          disabled={isExporting}
+        >
+          {isExporting ? 'Exporting...' : 'Download My Data'}
+        </Button>
+      </CardContent>
+    </Card>
+  );
+}