feat(auth): 添加登录验证到食物记录相关功能

- 在食物拍照、语音记录和营养成分分析功能中添加登录验证
- 使用 ensureLoggedIn 方法确保用户已登录后再调用服务端接口
- 使用 pushIfAuthedElseLogin 方法处理需要登录的页面导航
- 添加新的营养图标资源
- 在路由常量中添加 FOOD_CAMERA 路由定义
- 更新 Memory Bank 任务文档，记录登录验证和路由常量管理的实现模式

app/food/camera.tsx

@@ -1,5 +1,6 @@
 import { HeaderBar } from '@/components/ui/HeaderBar';
 import { Colors } from '@/constants/Colors';
+import { useAuthGuard } from '@/hooks/useAuthGuard';
 import { useSafeAreaTop } from '@/hooks/useSafeAreaWithPadding';
 import { Ionicons } from '@expo/vector-icons';
 import { CameraType, CameraView, useCameraPermissions } from 'expo-camera';
@@ -24,6 +25,7 @@ export default function FoodCameraScreen() {
   const router = useRouter();
   const params = useLocalSearchParams<{ mealType?: string }>();
   const cameraRef = useRef<CameraView>(null);
+  const { ensureLoggedIn } = useAuthGuard();
 
   const [currentMealType, setCurrentMealType] = useState<MealType>(
     (params.mealType as MealType) || 'dinner'
@@ -103,9 +105,12 @@ export default function FoodCameraScreen() {
         });
 
         if (photo) {
-          // 跳转到食物识别页面
+          // 先验证登录状态，再跳转到食物识别页面
           console.log('照片拍摄成功:', photo.uri);
-          router.replace(`/food/food-recognition?imageUri=${encodeURIComponent(photo.uri)}&mealType=${currentMealType}`);
+          const isLoggedIn = await ensureLoggedIn();
+          if (isLoggedIn) {
+            router.replace(`/food/food-recognition?imageUri=${encodeURIComponent(photo.uri)}&mealType=${currentMealType}`);
+          }
         }
       } catch (error) {
         console.error('拍照失败:', error);
@@ -127,7 +132,11 @@ export default function FoodCameraScreen() {
       if (!result.canceled && result.assets[0]) {
         const imageUri = result.assets[0].uri;
         console.log('从相册选择的照片:', imageUri);
-        router.push(`/food/food-recognition?imageUri=${encodeURIComponent(imageUri)}&mealType=${currentMealType}`);
+        // 先验证登录状态，再跳转到食物识别页面
+        const isLoggedIn = await ensureLoggedIn();
+        if (isLoggedIn) {
+          router.push(`/food/food-recognition?imageUri=${encodeURIComponent(imageUri)}&mealType=${currentMealType}`);
+        }
       }
     } catch (error) {
       console.error('选择照片失败:', error);