feat: 添加食物分析结果页面的图片预览功能，优化记录栏显示逻辑

app/food/camera.tsx

@@ -159,21 +159,23 @@ export default function FoodCameraScreen() {
         <View style={styles.cameraFrameContainer}>
           <Text style={styles.hintText}>确保食物在取景框内</Text>
 
-          {/* 相机取景框 */}
-          <View style={styles.cameraFrame}>
-            <CameraView
-              ref={cameraRef}
-              style={styles.cameraView}
-              facing={facing}
-            >
-              {/* 取景框装饰 */}
-              <View style={styles.viewfinderOverlay}>
-                <View style={[styles.corner, styles.topLeft]} />
-                <View style={[styles.corner, styles.topRight]} />
-                <View style={[styles.corner, styles.bottomLeft]} />
-                <View style={[styles.corner, styles.bottomRight]} />
-              </View>
-            </CameraView>
+          {/* 相机取景框包装器 */}
+          <View style={styles.cameraWrapper}>
+            {/* 相机取景框 */}
+            <View style={styles.cameraFrame}>
+              <CameraView
+                ref={cameraRef}
+                style={styles.cameraView}
+                facing={facing}
+              />
+            </View>
+            {/* 取景框装饰 - 放在外层避免被截断 */}
+            <View style={styles.viewfinderOverlay}>
+              <View style={[styles.corner, styles.topLeft]} />
+              <View style={[styles.corner, styles.topRight]} />
+              <View style={[styles.corner, styles.bottomLeft]} />
+              <View style={[styles.corner, styles.bottomRight]} />
+            </View>
           </View>
         </View>
 
@@ -294,21 +296,29 @@ const styles = StyleSheet.create({
     alignItems: 'center',
     paddingHorizontal: 20,
   },
+  cameraWrapper: {
+    width: 300,
+    height: 300,
+    position: 'relative',
+  },
   cameraFrame: {
     width: 300,
     height: 300,
     borderRadius: 20,
     overflow: 'hidden',
-    borderWidth: 3,
-    borderColor: '#FFF',
     backgroundColor: '#000',
   },
   cameraView: {
     flex: 1,
   },
   viewfinderOverlay: {
-    flex: 1,
-    position: 'relative',
+    position: 'absolute',
+    top: 0,
+    left: 0,
+    right: 0,
+    bottom: 0,
+    zIndex: 1,
+    pointerEvents: 'none',
   },
   camera: {
     flex: 1,