feat: 新增基础代谢率功能及相关组件

- 在健康数据中引入基础代谢率的读取和展示，支持用户记录健身进度
- 更新统计页面，替换BMI卡片为基础代谢卡片，提升用户体验
- 优化健康数据获取逻辑，确保基础代谢数据的准确性
- 更新权限描述，明确应用对健康数据的访问需求

components/WeightHistoryCard.tsx

@@ -2,13 +2,18 @@ import { Colors } from '@/constants/Colors';
 import { ROUTES } from '@/constants/Routes';
 import { useAppDispatch, useAppSelector } from '@/hooks/redux';
 import { useAuthGuard } from '@/hooks/useAuthGuard';
+import { useColorScheme } from '@/hooks/useColorScheme';
 import { fetchWeightHistory } from '@/store/userSlice';
+import { BMI_CATEGORIES, canCalculateBMI, getBMIResult } from '@/utils/bmi';
 import { Ionicons } from '@expo/vector-icons';
 import dayjs from 'dayjs';
+import { LinearGradient } from 'expo-linear-gradient';
 import React, { useEffect, useState } from 'react';
 import {
   Dimensions,
   Image,
+  Modal,
+  ScrollView,
   StyleSheet,
   Text,
   TouchableOpacity,
@@ -37,14 +42,28 @@ export function WeightHistoryCard() {
   const weightHistory = useAppSelector((s) => s.user.weightHistory);
   const [isLoading, setIsLoading] = useState(false);
   const [showChart, setShowChart] = useState(false);
+  const [showBMIModal, setShowBMIModal] = useState(false);
 
   // 动画相关状态
   const animationProgress = useSharedValue(0);
   const [isAnimating, setIsAnimating] = useState(false);
 
   const { pushIfAuthedElseLogin } = useAuthGuard();
+  const colorScheme = useColorScheme();
+  const themeColors = Colors[colorScheme ?? 'light'];
 
   const hasWeight = userProfile?.weight && parseFloat(userProfile.weight) > 0;
+  const hasHeight = userProfile?.height && parseFloat(userProfile.height) > 0;
+  
+  // BMI 计算
+  const canCalculate = canCalculateBMI(
+    userProfile?.weight ? parseFloat(userProfile.weight) : undefined,
+    userProfile?.height ? parseFloat(userProfile.height) : undefined
+  );
+  
+  const bmiResult = canCalculate && userProfile?.weight && userProfile?.height
+    ? getBMIResult(parseFloat(userProfile.weight), parseFloat(userProfile.height))
+    : null;
 
   useEffect(() => {
     if (hasWeight) {
@@ -67,6 +86,14 @@ export function WeightHistoryCard() {
     pushIfAuthedElseLogin(ROUTES.TAB_COACH);
   };
 
+  const handleShowBMIModal = () => {
+    setShowBMIModal(true);
+  };
+
+  const handleHideBMIModal = () => {
+    setShowBMIModal(false);
+  };
+
   // 切换图表显示状态的动画函数
   const toggleChart = () => {
     if (isAnimating) return; // 防止动画期间重复触发
@@ -314,9 +341,26 @@ export function WeightHistoryCard() {
               <View style={styles.summaryItem}>
                 <Text style={styles.summaryLabel}>变化范围</Text>
                 <Text style={styles.summaryValue}>
-                  {minWeight.toFixed(1)}-{maxWeight.toFixed(1)}kg
+                  {minWeight.toFixed(1)}-{maxWeight.toFixed(1)}
                 </Text>
               </View>
+              {bmiResult && (
+                <View style={styles.summaryItem}>
+                  <Text style={styles.summaryLabel}>BMI</Text>
+                  <View style={styles.bmiValueContainer}>
+                    <Text style={[styles.bmiValue, { color: bmiResult.color }]}>
+                      {bmiResult.value}
+                    </Text>
+                    <TouchableOpacity
+                      onPress={handleShowBMIModal}
+                      style={styles.bmiInfoButton}
+                      hitSlop={{ top: 10, bottom: 10, left: 10, right: 10 }}
+                    >
+                      <Ionicons name="information-circle-outline" size={12} color="#9AA3AE" />
+                    </TouchableOpacity>
+                  </View>
+                </View>
+              )}
             </View>
           </Animated.View>
 
@@ -418,6 +462,107 @@ export function WeightHistoryCard() {
           </Animated.View>
         </Animated.View>
       )}
+
+      {/* BMI 信息弹窗 */}
+      <Modal
+        visible={showBMIModal}
+        animationType="slide"
+        presentationStyle="pageSheet"
+        onRequestClose={handleHideBMIModal}
+      >
+        <LinearGradient
+          colors={[themeColors.backgroundGradientStart, themeColors.backgroundGradientEnd]}
+          style={styles.bmiModalContainer}
+          start={{ x: 0, y: 0 }}
+          end={{ x: 0, y: 1 }}
+        >
+          <ScrollView style={styles.bmiModalContent} showsVerticalScrollIndicator={false}>
+            {/* 标题 */}
+            <Text style={styles.bmiModalTitle}>BMI 指数说明</Text>
+
+            {/* 介绍部分 */}
+            <View style={styles.bmiModalIntroSection}>
+              <Text style={styles.bmiModalDescription}>
+                BMI（身体质量指数）是评估体重与身高关系的国际通用健康指标
+              </Text>
+              <View style={styles.bmiModalFormulaContainer}>
+                <Text style={styles.bmiModalFormulaText}>
+                  计算公式：体重(kg) ÷ 身高²(m)
+                </Text>
+              </View>
+            </View>
+
+            {/* BMI 分类标准 */}
+            <Text style={styles.bmiModalSectionTitle}>BMI 分类标准</Text>
+
+            <View style={styles.bmiModalStatsCard}>
+              {BMI_CATEGORIES.map((category, index) => {
+                const colors = [
+                  { bg: '#FEF3C7', text: '#B45309', border: '#F59E0B' }, // 偏瘦
+                  { bg: '#E8F5E8', text: Colors.light.accentGreenDark, border: Colors.light.accentGreen }, // 正常
+                  { bg: '#FEF3C7', text: '#B45309', border: '#F59E0B' }, // 超重
+                  { bg: '#FEE2E2', text: '#B91C1C', border: '#EF4444' }  // 肥胖
+                ][index];
+
+                return (
+                  <View key={index} style={[styles.bmiModalStatItem, { backgroundColor: colors.bg, borderColor: colors.border }]}>
+                    <View style={styles.bmiModalStatHeader}>
+                      <Text style={[styles.bmiModalStatTitle, { color: colors.text }]}>
+                        {category.name}
+                      </Text>
+                      <Text style={[styles.bmiModalStatRange, { color: colors.text }]}>
+                        {category.range}
+                      </Text>
+                    </View>
+                    <Text style={[styles.bmiModalStatAdvice, { color: colors.text }]}>
+                      {category.advice}
+                    </Text>
+                  </View>
+                );
+              })}
+            </View>
+
+            {/* 健康建议 */}
+            <Text style={styles.bmiModalSectionTitle}>健康建议</Text>
+            <View style={styles.bmiModalHealthTips}>
+              <View style={styles.bmiModalTipsItem}>
+                <Ionicons name="nutrition-outline" size={20} color="#3B82F6" />
+                <Text style={styles.bmiModalTipsText}>保持均衡饮食，控制热量摄入</Text>
+              </View>
+              <View style={styles.bmiModalTipsItem}>
+                <Ionicons name="walk-outline" size={20} color="#3B82F6" />
+                <Text style={styles.bmiModalTipsText}>每周至少150分钟中等强度运动</Text>
+              </View>
+              <View style={styles.bmiModalTipsItem}>
+                <Ionicons name="moon-outline" size={20} color="#3B82F6" />
+                <Text style={styles.bmiModalTipsText}>保证7-9小时充足睡眠</Text>
+              </View>
+              <View style={styles.bmiModalTipsItem}>
+                <Ionicons name="calendar-outline" size={20} color="#3B82F6" />
+                <Text style={styles.bmiModalTipsText}>定期监测体重变化，及时调整</Text>
+              </View>
+            </View>
+
+            {/* 免责声明 */}
+            <View style={styles.bmiModalDisclaimer}>
+              <Ionicons name="information-circle-outline" size={16} color="#6B7280" />
+              <Text style={styles.bmiModalDisclaimerText}>
+                BMI 仅供参考，不能反映肌肉量、骨密度等指标。如有健康疑问，请咨询专业医生。
+              </Text>
+            </View>
+          </ScrollView>
+
+          {/* 底部继续按钮 */}
+          <View style={styles.bmiModalBottomContainer}>
+            <TouchableOpacity style={styles.bmiModalContinueButton} onPress={handleHideBMIModal}>
+              <View style={styles.bmiModalButtonBackground}>
+                <Text style={styles.bmiModalButtonText}>继续</Text>
+              </View>
+            </TouchableOpacity>
+            <View style={styles.bmiModalHomeIndicator} />
+          </View>
+        </LinearGradient>
+      </Modal>
     </View>
   );
 }
@@ -546,20 +691,178 @@ const styles = StyleSheet.create({
   },
   summaryRow: {
     flexDirection: 'row',
-    justifyContent: 'space-around',
+    justifyContent: 'space-between',
     marginBottom: 0,
+    flexWrap: 'wrap',
+    gap: 8,
   },
   summaryItem: {
     alignItems: 'center',
+    flex: 1,
+    minWidth: 0,
   },
   summaryLabel: {
-    fontSize: 12,
+    fontSize: 11,
     color: '#687076',
-    marginBottom: 4,
+    marginBottom: 3,
   },
   summaryValue: {
-    fontSize: 14,
+    fontSize: 13,
     fontWeight: '700',
     color: '#192126',
   },
+  
+  // BMI 相关样式
+  bmiValueContainer: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    gap: 1,
+  },
+  bmiValue: {
+    fontSize: 12,
+    fontWeight: '700',
+  },
+  bmiInfoButton: {
+    padding: 0,
+  },
+  bmiStatusBadge: {
+    paddingHorizontal: 8,
+    paddingVertical: 2,
+    borderRadius: 8,
+  },
+  bmiStatusText: {
+    fontSize: 10,
+    fontWeight: '700',
+  },
+  
+  // BMI 弹窗样式
+  bmiModalContainer: {
+    flex: 1,
+  },
+  bmiModalContent: {
+    flex: 1,
+    padding: 20,
+  },
+  bmiModalTitle: {
+    fontSize: 28,
+    fontWeight: '800',
+    color: '#111827',
+    textAlign: 'center',
+    marginBottom: 24,
+    letterSpacing: -0.5,
+  },
+  bmiModalIntroSection: {
+    marginBottom: 32,
+  },
+  bmiModalDescription: {
+    fontSize: 16,
+    color: '#374151',
+    lineHeight: 24,
+    textAlign: 'center',
+    marginBottom: 16,
+  },
+  bmiModalFormulaContainer: {
+    backgroundColor: '#F3F4F6',
+    borderRadius: 12,
+    padding: 16,
+    alignItems: 'center',
+  },
+  bmiModalFormulaText: {
+    fontSize: 14,
+    fontWeight: '600',
+    color: '#374151',
+  },
+  bmiModalSectionTitle: {
+    fontSize: 20,
+    fontWeight: '700',
+    color: '#111827',
+    marginBottom: 16,
+    letterSpacing: -0.5,
+  },
+  bmiModalStatsCard: {
+    marginBottom: 32,
+  },
+  bmiModalStatItem: {
+    borderRadius: 12,
+    padding: 16,
+    marginBottom: 12,
+    borderWidth: 1,
+  },
+  bmiModalStatHeader: {
+    flexDirection: 'row',
+    justifyContent: 'space-between',
+    alignItems: 'center',
+    marginBottom: 8,
+  },
+  bmiModalStatTitle: {
+    fontSize: 16,
+    fontWeight: '700',
+  },
+  bmiModalStatRange: {
+    fontSize: 14,
+    fontWeight: '600',
+  },
+  bmiModalStatAdvice: {
+    fontSize: 14,
+    lineHeight: 20,
+  },
+  bmiModalHealthTips: {
+    marginBottom: 32,
+  },
+  bmiModalTipsItem: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    marginBottom: 16,
+    paddingHorizontal: 16,
+    paddingVertical: 12,
+    backgroundColor: '#F8FAFC',
+    borderRadius: 12,
+  },
+  bmiModalTipsText: {
+    fontSize: 14,
+    color: '#374151',
+    marginLeft: 12,
+    flex: 1,
+    lineHeight: 20,
+  },
+  bmiModalDisclaimer: {
+    flexDirection: 'row',
+    alignItems: 'flex-start',
+    backgroundColor: '#FEF3C7',
+    borderRadius: 12,
+    padding: 16,
+    marginBottom: 20,
+  },
+  bmiModalDisclaimerText: {
+    fontSize: 13,
+    color: '#B45309',
+    marginLeft: 8,
+    flex: 1,
+    lineHeight: 18,
+  },
+  bmiModalBottomContainer: {
+    padding: 20,
+    paddingBottom: 34,
+  },
+  bmiModalContinueButton: {
+    marginBottom: 8,
+  },
+  bmiModalButtonBackground: {
+    backgroundColor: '#192126',
+    borderRadius: 16,
+    paddingVertical: 16,
+    alignItems: 'center',
+  },
+  bmiModalButtonText: {
+    fontSize: 16,
+    fontWeight: '700',
+    color: '#FFFFFF',
+  },
+  bmiModalHomeIndicator: {
+    height: 5,
+    backgroundColor: '#D1D5DB',
+    borderRadius: 3,
+    alignSelf: 'center',
+    width: 36,
+  },
 });