feat(background-task): 完善iOS后台任务系统并优化断食通知和UI体验

- 修复iOS后台任务注册时机问题，确保任务能正常触发
- 添加后台任务调试辅助工具和完整测试指南
- 优化断食通知系统，增加防抖机制避免频繁重调度
- 改进断食自动续订逻辑，使用固定时间而非相对时间计算
- 优化统计页面布局，添加身体指标section标题
- 增强饮水详情页面视觉效果，改进卡片样式和配色
- 添加用户反馈入口到个人设置页面
- 完善锻炼摘要卡片条件渲染逻辑
- 增强日志记录和错误处理机制

这些改进显著提升了应用的稳定性、性能和用户体验，特别是在iOS后台任务执行和断食功能方面。

app/(tabs)/fasting.tsx

@@ -8,23 +8,23 @@ import { useAppDispatch, useAppSelector } from '@/hooks/redux';
 import { useCountdown } from '@/hooks/useCountdown';
 import { useFastingNotifications } from '@/hooks/useFastingNotifications';
 import {
-  clearActiveSchedule,
-  rescheduleActivePlan,
-  scheduleFastingPlan,
-  selectActiveFastingPlan,
-  selectActiveFastingSchedule,
+    clearActiveSchedule,
+    rescheduleActivePlan,
+    scheduleFastingPlan,
+    selectActiveFastingPlan,
+    selectActiveFastingSchedule,
 } from '@/store/fastingSlice';
 import {
-  buildDisplayWindow,
-  calculateFastingWindow,
-  getFastingPhase,
-  getPhaseLabel,
-  loadPreferredPlanId,
-  savePreferredPlanId
+    buildDisplayWindow,
+    calculateFastingWindow,
+    getFastingPhase,
+    getPhaseLabel,
+    loadPreferredPlanId,
+    savePreferredPlanId
 } from '@/utils/fasting';
 import { useFocusEffect } from '@react-navigation/native';
-import { useRouter } from 'expo-router';
 import dayjs from 'dayjs';
+import { useRouter } from 'expo-router';
 import React, { useCallback, useEffect, useMemo, useState } from 'react';
 import { ScrollView, StyleSheet, Text, View } from 'react-native';
 import { useSafeAreaInsets } from 'react-native-safe-area-context';
@@ -87,8 +87,19 @@ export default function FastingTabScreen() {
   } = useFastingNotifications(activeSchedule, currentPlan);
 
   // 每次进入页面时验证通知
+  // 添加节流机制，避免频繁触发验证
+  const lastVerifyTimeRef = React.useRef<number>(0);
   useFocusEffect(
     useCallback(() => {
+      const now = Date.now();
+      const timeSinceLastVerify = now - lastVerifyTimeRef.current;
+      
+      // 如果距离上次验证不足 30 秒，跳过本次验证
+      if (timeSinceLastVerify < 30000) {
+        return;
+      }
+      
+      lastVerifyTimeRef.current = now;
       verifyAndSync();
     }, [verifyAndSync])
   );
@@ -155,6 +166,8 @@ export default function FastingTabScreen() {
     }
   }, [notificationsReady, notificationsLoading, notificationError, notificationIds, lastSyncTime, activeSchedule?.startISO, currentPlan?.id]);
 
+  // 自动续订断食周期
+  // 修改为使用每日固定时间，而非相对时间计算
   useEffect(() => {
     if (!activeSchedule || !currentPlan) return;
     if (phase !== 'completed') return;
@@ -166,38 +179,42 @@ export default function FastingTabScreen() {
     const now = dayjs();
     if (now.isBefore(end)) return;
 
-    const fastingHours = currentPlan.fastingHours;
-    const eatingHours = currentPlan.eatingHours;
-    const cycleHours = fastingHours + eatingHours;
-
-    if (fastingHours <= 0 || cycleHours <= 0) return;
-
-    let nextStart = start;
-    let nextEnd = end;
-    let iterations = 0;
-    const maxIterations = 60;
-
-    while (!now.isBefore(nextEnd)) {
-      nextStart = nextStart.add(cycleHours, 'hour');
-      nextEnd = nextStart.add(fastingHours, 'hour');
-      iterations += 1;
-
-      if (iterations >= maxIterations) {
-        if (__DEV__) {
-          console.warn('自动续订断食周期失败: 超出最大迭代次数', {
-            start: activeSchedule.startISO,
-            end: activeSchedule.endISO,
-            planId: currentPlan.id,
-          });
-        }
-        return;
+    // 检查是否在短时间内已经续订过，避免重复续订
+    const timeSinceEnd = now.diff(end, 'minute');
+    if (timeSinceEnd > 60) {
+      // 如果周期结束超过1小时，说明用户可能不再需要自动续订
+      if (__DEV__) {
+        console.log('断食周期结束超过1小时，不自动续订');
       }
+      return;
     }
 
-    if (iterations === 0) return;
+    // 使用每日固定时间计算下一个周期
+    // 保持原始的开始时间（小时和分钟），只增加日期
+    const originalStartHour = start.hour();
+    const originalStartMinute = start.minute();
+    
+    // 计算下一个开始时间：明天的同一时刻
+    let nextStart = now.startOf('day').hour(originalStartHour).minute(originalStartMinute);
+    
+    // 如果计算出的时间在当前时间之前，则使用后天的同一时刻
+    if (nextStart.isBefore(now)) {
+      nextStart = nextStart.add(1, 'day');
+    }
+
+    const nextEnd = nextStart.add(currentPlan.fastingHours, 'hour');
+
+    if (__DEV__) {
+      console.log('自动续订断食周期:', {
+        oldStart: start.format('YYYY-MM-DD HH:mm'),
+        oldEnd: end.format('YYYY-MM-DD HH:mm'),
+        nextStart: nextStart.format('YYYY-MM-DD HH:mm'),
+        nextEnd: nextEnd.format('YYYY-MM-DD HH:mm'),
+      });
+    }
 
     dispatch(rescheduleActivePlan({
-      start: nextStart.toDate().toISOString(),
+      start: nextStart.toISOString(),
       origin: 'auto',
     }));
   }, [dispatch, activeSchedule, currentPlan, phase]);