feat: Apply localization to Track and Children pages (Phase 9 - Batch 2)

**Pages Localized:**
- Track main page: Activity selection menu with all tracking options
- Children page: Complete localization including age formatting with pluralization

**Translation Files:**
- Enhanced tracking.json: Added trackActivity, selectActivity, and activities keys
- Created children.json for all 5 languages with comprehensive strings
- Updated i18n config to include children namespace

**Key Features:**
- Localized age calculation with proper pluralization (year/years, month/months)
- All error messages translated
- Gender labels localized
- Properly formatted age display for all languages

**Languages Supported:**
- English, Spanish, French, Portuguese, Chinese (Simplified)

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

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

maternal-web/lib/i18n/config.ts

@@ -6,6 +6,7 @@ import LanguageDetector from 'i18next-browser-languagedetector';
 import enCommon from '@/locales/en/common.json';
 import enDashboard from '@/locales/en/dashboard.json';
 import enTracking from '@/locales/en/tracking.json';
+import enChildren from '@/locales/en/children.json';
 import enAi from '@/locales/en/ai.json';
 import enAuth from '@/locales/en/auth.json';
 import enSettings from '@/locales/en/settings.json';
@@ -15,6 +16,7 @@ import enErrors from '@/locales/en/errors.json';
 import esCommon from '@/locales/es/common.json';
 import esDashboard from '@/locales/es/dashboard.json';
 import esTracking from '@/locales/es/tracking.json';
+import esChildren from '@/locales/es/children.json';
 import esAi from '@/locales/es/ai.json';
 import esAuth from '@/locales/es/auth.json';
 import esSettings from '@/locales/es/settings.json';
@@ -24,6 +26,7 @@ import esErrors from '@/locales/es/errors.json';
 import frCommon from '@/locales/fr/common.json';
 import frDashboard from '@/locales/fr/dashboard.json';
 import frTracking from '@/locales/fr/tracking.json';
+import frChildren from '@/locales/fr/children.json';
 import frAi from '@/locales/fr/ai.json';
 import frAuth from '@/locales/fr/auth.json';
 import frSettings from '@/locales/fr/settings.json';
@@ -33,6 +36,7 @@ import frErrors from '@/locales/fr/errors.json';
 import ptCommon from '@/locales/pt/common.json';
 import ptDashboard from '@/locales/pt/dashboard.json';
 import ptTracking from '@/locales/pt/tracking.json';
+import ptChildren from '@/locales/pt/children.json';
 import ptAi from '@/locales/pt/ai.json';
 import ptAuth from '@/locales/pt/auth.json';
 import ptSettings from '@/locales/pt/settings.json';
@@ -42,6 +46,7 @@ import ptErrors from '@/locales/pt/errors.json';
 import zhCommon from '@/locales/zh/common.json';
 import zhDashboard from '@/locales/zh/dashboard.json';
 import zhTracking from '@/locales/zh/tracking.json';
+import zhChildren from '@/locales/zh/children.json';
 import zhAi from '@/locales/zh/ai.json';
 import zhAuth from '@/locales/zh/auth.json';
 import zhSettings from '@/locales/zh/settings.json';
@@ -53,6 +58,7 @@ export const resources = {
     common: enCommon,
     dashboard: enDashboard,
     tracking: enTracking,
+    children: enChildren,
     ai: enAi,
     auth: enAuth,
     settings: enSettings,
@@ -63,6 +69,7 @@ export const resources = {
     common: esCommon,
     dashboard: esDashboard,
     tracking: esTracking,
+    children: esChildren,
     ai: esAi,
     auth: esAuth,
     settings: esSettings,
@@ -73,6 +80,7 @@ export const resources = {
     common: frCommon,
     dashboard: frDashboard,
     tracking: frTracking,
+    children: frChildren,
     ai: frAi,
     auth: frAuth,
     settings: frSettings,
@@ -83,6 +91,7 @@ export const resources = {
     common: ptCommon,
     dashboard: ptDashboard,
     tracking: ptTracking,
+    children: ptChildren,
     ai: ptAi,
     auth: ptAuth,
     settings: ptSettings,
@@ -93,6 +102,7 @@ export const resources = {
     common: zhCommon,
     dashboard: zhDashboard,
     tracking: zhTracking,
+    children: zhChildren,
     ai: zhAi,
     auth: zhAuth,
     settings: zhSettings,