feat(fasting): 新增轻断食功能模块

新增完整的轻断食功能，包括：
- 断食计划列表和详情页面，支持12-12、14-10、16-8、18-6四种计划
- 断食状态实时追踪和倒计时显示
- 自定义开始时间选择器
- 断食通知提醒功能
- Redux状态管理和数据持久化
- 新增tab导航入口和路由配置

components/fasting/FastingPlanList.tsx

@@ -0,0 +1,185 @@
+import type { FastingPlan } from '@/constants/Fasting';
+import { Colors } from '@/constants/Colors';
+import { IconSymbol } from '@/components/ui/IconSymbol';
+import { useColorScheme } from '@/hooks/useColorScheme';
+import React, { useMemo } from 'react';
+import {
+  ScrollView,
+  StyleSheet,
+  Text,
+  TouchableOpacity,
+  View,
+} from 'react-native';
+
+type FastingPlanListProps = {
+  plans: FastingPlan[];
+  activePlanId?: string | null;
+  onSelectPlan: (plan: FastingPlan) => void;
+};
+
+const difficultyLabel: Record<FastingPlan['difficulty'], string> = {
+  新手: '适合入门',
+  进阶: '脂代提升',
+  强化: '平台突破',
+};
+
+export function FastingPlanList({ plans, activePlanId, onSelectPlan }: FastingPlanListProps) {
+  const theme = useColorScheme() ?? 'light';
+  const colors = Colors[theme];
+
+  const sortedPlans = useMemo(
+    () => plans.slice().sort((a, b) => a.fastingHours - b.fastingHours),
+    [plans]
+  );
+
+  return (
+    <View style={styles.wrapper}>
+      <View style={styles.headerRow}>
+        <Text style={styles.headerTitle}>单日计划</Text>
+        <View style={styles.headerBadge}>
+          <Text style={styles.headerBadgeText}>精选</Text>
+        </View>
+      </View>
+      <ScrollView
+        horizontal
+        showsHorizontalScrollIndicator={false}
+        contentContainerStyle={styles.scrollContent}
+      >
+        {sortedPlans.map((plan) => {
+          const isActive = plan.id === activePlanId;
+          return (
+            <TouchableOpacity
+              key={plan.id}
+              style={[
+                styles.card,
+                {
+                  backgroundColor: plan.theme.backdrop,
+                  borderColor: isActive ? plan.theme.accent : 'transparent',
+                },
+              ]}
+              activeOpacity={0.85}
+              onPress={() => onSelectPlan(plan)}
+            >
+              <View style={styles.cardTopRow}>
+                <View style={[styles.difficultyPill, { backgroundColor: `${plan.theme.accent}1A` }]}>
+                  <Text style={[styles.difficultyText, { color: plan.theme.accent }]}>
+                    {plan.difficulty}
+                  </Text>
+                </View>
+                {plan.badge && (
+                  <View style={[styles.badgePill, { backgroundColor: `${plan.theme.accent}26` }]}>
+                    <Text style={[styles.badgeText, { color: plan.theme.accent }]}>
+                      {plan.badge}
+                    </Text>
+                  </View>
+                )}
+              </View>
+              <Text style={styles.cardTitle}>{plan.title}</Text>
+              <Text style={styles.cardSubtitle}>{plan.subtitle}</Text>
+              <View style={styles.metaRow}>
+                <View style={styles.metaItem}>
+                  <IconSymbol name="chart.pie.fill" color={colors.icon} size={16} />
+                  <Text style={styles.metaText}>{plan.fastingHours} 小时断食</Text>
+                </View>
+                <View style={styles.metaItem}>
+                  <IconSymbol name="flag.fill" color={colors.icon} size={16} />
+                  <Text style={styles.metaText}>{difficultyLabel[plan.difficulty]}</Text>
+                </View>
+              </View>
+            </TouchableOpacity>
+          );
+        })}
+      </ScrollView>
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  wrapper: {
+    marginTop: 32,
+  },
+  headerRow: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    justifyContent: 'space-between',
+    marginBottom: 12,
+    paddingHorizontal: 4,
+  },
+  headerTitle: {
+    fontSize: 18,
+    fontWeight: '700',
+    color: '#2E3142',
+  },
+  headerBadge: {
+    paddingHorizontal: 12,
+    paddingVertical: 6,
+    borderRadius: 14,
+    backgroundColor: 'rgba(53, 52, 69, 0.08)',
+  },
+  headerBadgeText: {
+    fontSize: 12,
+    fontWeight: '600',
+    color: '#353445',
+  },
+  scrollContent: {
+    paddingRight: 20,
+  },
+  card: {
+    width: 220,
+    borderRadius: 24,
+    paddingVertical: 18,
+    paddingHorizontal: 18,
+    marginRight: 16,
+    borderWidth: 2,
+  },
+  cardTopRow: {
+    flexDirection: 'row',
+    justifyContent: 'space-between',
+    alignItems: 'center',
+    marginBottom: 12,
+  },
+  difficultyPill: {
+    paddingHorizontal: 12,
+    paddingVertical: 6,
+    borderRadius: 16,
+  },
+  difficultyText: {
+    fontSize: 12,
+    fontWeight: '600',
+  },
+  badgePill: {
+    paddingHorizontal: 10,
+    paddingVertical: 6,
+    borderRadius: 14,
+  },
+  badgeText: {
+    fontSize: 11,
+    fontWeight: '600',
+  },
+  cardTitle: {
+    fontSize: 16,
+    fontWeight: '700',
+    color: '#2E3142',
+    marginBottom: 6,
+  },
+  cardSubtitle: {
+    fontSize: 13,
+    fontWeight: '500',
+    color: '#5B6572',
+    marginBottom: 12,
+  },
+  metaRow: {
+    marginTop: 'auto',
+  },
+  metaItem: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    marginBottom: 6,
+  },
+  metaText: {
+    marginLeft: 6,
+    fontSize: 12,
+    color: '#5B6572',
+    fontWeight: '500',
+  },
+});