feat: Apply localization to Login, Dashboard, and Navigation (Phase 9 - Batch 1)

**Pages Localized:**
- Login page: All UI strings (titles, labels, buttons, links)
- Dashboard page: Welcome message, quick actions, daily summary, predictions
- AppShell: Connection status and presence indicators
- MobileNav: Menu items and app branding
- TabBar: Bottom navigation labels

**Translation Files:**
- Created dashboard.json for all 5 languages (en, es, fr, pt, zh)
- Enhanced common.json with navigation and connection strings
- Updated i18n config to include dashboard namespace

**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/locales/zh/common.json

@@ -57,10 +57,23 @@
   },
   "navigation": {
     "home": "首页",
+    "dashboard": "仪表板",
     "tracking": "追踪",
+    "trackActivity": "记录活动",
+    "track": "记录",
     "ai": "AI助手",
+    "aiChat": "AI聊天",
     "family": "家庭",
     "insights": "分析",
-    "settings": "设置"
+    "children": "儿童",
+    "settings": "设置",
+    "logout": "退出登录"
+  },
+  "connection": {
+    "syncActive": "实时同步活动",
+    "syncDisconnected": "实时同步已断开",
+    "live": "在线",
+    "offline": "离线",
+    "familyMembersOnline": "{{count}}位家庭成员在线"
   }
 }