feat: Complete Spanish, French, Portuguese, Chinese localization and add German/Italian support

- Updated all Spanish (es) translation files with comprehensive translations for tracking, AI, family, insights, children, and settings pages
- Updated French (fr), Portuguese (pt), and Chinese (zh) translations to match English structure
- Added German (de) and Italian (it) language support with complete translation files
- Fixed medicine tracker route from /track/medication to /track/medicine
- Updated i18n config to support 7 languages: en, es, fr, pt, zh, de, it
- All tracking pages now fully localized: sleep, feeding, diaper, medicine, activity
- AI assistant interface fully translated with thinking messages and suggested questions
- Family management and insights pages now support all languages

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

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

maternal-web/app/(auth)/onboarding/page.tsx

@@ -15,14 +15,26 @@ import {
   Alert,
   CircularProgress,
   MenuItem,
+  Card,
+  CardActionArea,
+  CardContent,
+  Radio,
+  RadioGroup,
+  FormControlLabel,
+  FormControl,
+  Grid,
 } from '@mui/material';
-import { ArrowBack, ArrowForward, Check } from '@mui/icons-material';
+import { ArrowBack, ArrowForward, Check, Language, Straighten } from '@mui/icons-material';
 import { motion, AnimatePresence } from 'framer-motion';
 import { useRouter } from 'next/navigation';
 import { useAuth } from '@/lib/auth/AuthContext';
 import { childrenApi } from '@/lib/api/children';
+import { useLocale, MeasurementSystem } from '@/hooks/useLocale';
+import { useTranslation } from '@/hooks/useTranslation';
+import { supportedLanguages } from '@/lib/i18n/config';
+import { usersApi } from '@/lib/api/users';
 
-const steps = ['Welcome', 'Add Child', 'Invite Family', 'Notifications'];
+const steps = ['Welcome', 'Language', 'Measurements', 'Add Child', 'Complete'];
 
 export default function OnboardingPage() {
   const [activeStep, setActiveStep] = useState(0);