feat(i18n): 全面实现应用核心功能模块的国际化支持

- 新增 i18n 翻译资源，覆盖睡眠、饮水、体重、锻炼、用药 AI 识别、步数、健身圆环、基础代谢及设置等核心模块
- 重构相关页面及组件（如 SleepDetail, WaterDetail, WorkoutHistory 等）使用 `useI18n` 钩子替换硬编码文本
- 升级 `utils/date` 工具库与 `DateSelector` 组件，支持基于语言环境的日期格式化与显示
- 完善登录页、注销流程及权限申请弹窗的双语提示信息
- 优化部分页面的 UI 细节与字体样式以适配多语言显示

components/weight/WeightRecordCard.tsx

@@ -1,5 +1,6 @@
 import { Colors } from '@/constants/Colors';
 import { useColorScheme } from '@/hooks/useColorScheme';
+import { useI18n } from '@/hooks/useI18n';
 import { WeightHistoryItem } from '@/store/userSlice';
 import { Ionicons } from '@expo/vector-icons';
 import dayjs from 'dayjs';
@@ -20,6 +21,7 @@ export const WeightRecordCard: React.FC<WeightRecordCardProps> = ({
   onDelete,
   weightChange = 0
 }) => {
+  const { t } = useI18n();
   const swipeableRef = useRef<Swipeable>(null);
   const colorScheme = useColorScheme();
   const themeColors = Colors[colorScheme ?? 'light'];
@@ -27,15 +29,15 @@ export const WeightRecordCard: React.FC<WeightRecordCardProps> = ({
   // 处理删除操作
   const handleDelete = () => {
     Alert.alert(
-      '确认删除',
-      `确定要删除这条体重记录吗？此操作无法撤销。`,
+      t('weightRecords.card.deleteConfirmTitle'),
+      t('weightRecords.card.deleteConfirmMessage'),
       [
         {
-          text: '取消',
+          text: t('weightRecords.card.cancelButton'),
           style: 'cancel',
         },
         {
-          text: '删除',
+          text: t('weightRecords.card.deleteButton'),
           style: 'destructive',
           onPress: () => {
             const recordId = record.id || record.createdAt;
@@ -56,7 +58,7 @@ export const WeightRecordCard: React.FC<WeightRecordCardProps> = ({
         activeOpacity={0.8}
       >
         <Ionicons name="trash" size={20} color="#FFFFFF" />
-        <Text style={styles.deleteButtonText}>删除</Text>
+        <Text style={styles.deleteButtonText}>{t('weightRecords.card.deleteButton')}</Text>
       </TouchableOpacity>
     );
   };
@@ -73,7 +75,7 @@ export const WeightRecordCard: React.FC<WeightRecordCardProps> = ({
       >
         <View style={styles.recordHeader}>
           <Text style={[styles.recordDateTime, { color: themeColors.textSecondary }]}>
-            {dayjs(record.createdAt).format('MM月DD日 HH:mm')}
+            {dayjs(record.createdAt).format('MM[月]DD[日] HH:mm')}
           </Text>
           <TouchableOpacity
             style={styles.recordEditButton}
@@ -83,8 +85,8 @@ export const WeightRecordCard: React.FC<WeightRecordCardProps> = ({
           </TouchableOpacity>
         </View>
         <View style={styles.recordContent}>
-          <Text style={[styles.recordWeightLabel, { color: themeColors.textSecondary }]}>体重：</Text>
-          <Text style={[styles.recordWeightValue, { color: themeColors.text }]}>{record.weight}kg</Text>
+          <Text style={[styles.recordWeightLabel, { color: themeColors.textSecondary }]}>{t('weightRecords.card.weightLabel')}：</Text>
+          <Text style={[styles.recordWeightValue, { color: themeColors.text }]}>{record.weight}{t('weightRecords.modal.unit')}</Text>
           {Math.abs(weightChange) > 0 && (
             <View style={[
               styles.weightChangeTag,