Add biometric authentication enrollment UI

- Create biometric API client with WebAuthn methods
- Add BiometricSettings component for credential management
- Support Face ID, Touch ID, Windows Hello enrollment
- Display list of enrolled credentials with metadata
- Add/remove/rename biometric credentials
- Check browser and platform authenticator support
- Integrate into settings page with animations

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

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

maternal-web/app/settings/page.tsx

@@ -10,6 +10,7 @@ import { usersApi } from '@/lib/api/users';
 import { MFASettings } from '@/components/settings/MFASettings';
 import { SessionsManagement } from '@/components/settings/SessionsManagement';
 import { DeviceTrustManagement } from '@/components/settings/DeviceTrustManagement';
+import { BiometricSettings } from '@/components/settings/BiometricSettings';
 import { motion } from 'framer-motion';
 
 export default function SettingsPage() {
@@ -253,6 +254,17 @@ export default function SettingsPage() {
         </Box>
       </motion.div>
 
+      {/* Biometric Authentication */}
+      <motion.div
+        initial={{ opacity: 0, y: 20 }}
+        animate={{ opacity: 1, y: 0 }}
+        transition={{ duration: 0.4, delay: 0.36 }}
+      >
+        <Box sx={{ mb: 3 }}>
+          <BiometricSettings />
+        </Box>
+      </motion.div>
+
       {/* Account Actions */}
       <motion.div
         initial={{ opacity: 0, y: 20 }}