feat: 优化统计页面和BMI卡片，移除压力分析相关代码

- 在统计页面中移除压力分析模态框及相关状态管理，简化组件逻辑
- 更新BMI卡片，改进弹窗展示方式，增加渐变背景和健康建议
- 新增更新体重的功能，支持将体重数据写入健康数据中
- 优化压力计组件，调整数据展示逻辑，提升用户体验

app/(tabs)/statistics.tsx

@@ -3,7 +3,6 @@ import { BMICard } from '@/components/BMICard';
 import { CircularRing } from '@/components/CircularRing';
 import { NutritionRadarCard } from '@/components/NutritionRadarCard';
 import { ProgressBar } from '@/components/ProgressBar';
-import { StressAnalysisModal } from '@/components/StressAnalysisModal';
 import { StressMeter } from '@/components/StressMeter';
 import { WeightHistoryCard } from '@/components/WeightHistoryCard';
 import { Colors } from '@/constants/Colors';
@@ -87,9 +86,6 @@ export default function ExploreScreen() {
   const [nutritionSummary, setNutritionSummary] = useState<NutritionSummary | null>(null);
   const [isNutritionLoading, setIsNutritionLoading] = useState(false);
 
-  // 压力分析浮窗状态
-  const [showStressModal, setShowStressModal] = useState(false);
-
   // 记录最近一次请求的“日期键”，避免旧请求覆盖新结果
   const latestRequestKeyRef = useRef<string | null>(null);
 
@@ -209,15 +205,6 @@ export default function ExploreScreen() {
     }
   };
 
-  // 处理压力卡片点击
-  const handleStressCardPress = () => {
-    setShowStressModal(true);
-  };
-
-  // 关闭压力分析浮窗
-  const handleCloseStressModal = () => {
-    setShowStressModal(false);
-  };
 
   // 使用统一的渐变背景色
   const backgroundGradientColors = [colorTokens.backgroundGradientStart, colorTokens.backgroundGradientEnd] as const;
@@ -280,7 +267,7 @@ export default function ExploreScreen() {
                 value={hrvValue}
                 updateTime={hrvUpdateTime}
                 style={styles.masonryCard}
-                onPress={handleStressCardPress}
+                hrvValue={hrvValue}
               />
 
               <View style={[styles.masonryCard, styles.caloriesCard]}>
@@ -371,14 +358,6 @@ export default function ExploreScreen() {
 
         </ScrollView>
       </SafeAreaView>
-
-      {/* 压力分析浮窗 */}
-      <StressAnalysisModal
-        visible={showStressModal}
-        onClose={handleCloseStressModal}
-        hrvValue={hrvValue}
-        updateTime={hrvUpdateTime}
-      />
     </View>
   );
 }