feat(medications): 添加用药管理功能

- 新增用药标签页，包含完整的用药记录界面
- 实现用药卡片组件，支持状态显示（已服用/未服用/已错过）
- 增强日期选择器，添加"回到今天"快捷功能
- 添加用药相关的图标支持（pills.fill, plus）
- 集成用药路由配置，支持标签页导航

该功能为用户提供完整的用药管理体验，包括用药记录、状态跟踪和日期筛选等核心功能。

components/DateSelector.tsx

@@ -58,6 +58,17 @@ export const DateSelector: React.FC<DateSelectorProps> = ({
   const days = getMonthDaysZh(currentMonth);
   const monthTitle = externalMonthTitle ?? getMonthTitleZh(currentMonth);
 
+  // 判断当前选中的日期是否是今天
+  const isSelectedDateToday = () => {
+    const today = dayjs();
+    const selectedDate = days[selectedIndex]?.date;
+    
+    if (!selectedDate) return false;
+    
+    // 检查是否是同一天且在同一个月
+    return selectedDate.isSame(today, 'day') && currentMonth.isSame(today, 'month');
+  };
+
   // 滚动相关
   const daysScrollRef = useRef<ScrollView | null>(null);
   const [scrollWidth, setScrollWidth] = useState(0);
@@ -191,20 +202,47 @@ export const DateSelector: React.FC<DateSelectorProps> = ({
     }
   };
 
+  const handleGoToday = () => {
+    const today = dayjs();
+    setCurrentMonth(today);
+    const todayDays = getMonthDaysZh(today);
+    const newSelectedIndex = todayDays.findIndex(day => day.dayOfMonth === today.date());
+
+    if (newSelectedIndex !== -1) {
+      if (externalSelectedIndex === undefined) {
+        setInternalSelectedIndex(newSelectedIndex);
+      }
+      const todayDate = today.toDate();
+      setPickerDate(todayDate);
+      onDateSelect?.(newSelectedIndex, todayDate);
+    }
+  };
+
   return (
     <View style={[styles.container, containerStyle]}>
       {showMonthTitle && (
         <View style={styles.monthTitleContainer}>
           <Text style={styles.monthTitle}>{monthTitle}</Text>
-          {showCalendarIcon && (
-            <TouchableOpacity
-              onPress={openDatePicker}
-              style={styles.calendarIconButton}
-              activeOpacity={0.7}
-            >
-              <Ionicons name="calendar-outline" size={14} color="#666666" />
-            </TouchableOpacity>
-          )}
+          <View style={styles.monthActions}>
+            {!isSelectedDateToday() && (
+              <TouchableOpacity
+                onPress={handleGoToday}
+                style={styles.todayButton}
+                activeOpacity={0.8}
+              >
+                <Text style={styles.todayButtonText}>回到今天</Text>
+              </TouchableOpacity>
+            )}
+            {showCalendarIcon && (
+              <TouchableOpacity
+                onPress={openDatePicker}
+                style={styles.calendarIconButton}
+                activeOpacity={0.7}
+              >
+                <Ionicons name="calendar-outline" size={14} color="#666666" />
+              </TouchableOpacity>
+            )}
+          </View>
         </View>
       )}
 
@@ -305,9 +343,13 @@ const styles = StyleSheet.create({
   monthTitleContainer: {
     flexDirection: 'row',
     alignItems: 'center',
-    justifyContent: 'flex-start',
+    justifyContent: 'space-between',
     marginBottom: 8,
   },
+  monthActions: {
+    flexDirection: 'row',
+    alignItems: 'center',
+  },
   monthTitle: {
     fontSize: 20,
     fontWeight: '800',
@@ -318,6 +360,18 @@ const styles = StyleSheet.create({
     borderRadius: 6,
     marginLeft: 4
   },
+  todayButton: {
+    paddingHorizontal: 12,
+    paddingVertical: 6,
+    borderRadius: 12,
+    backgroundColor: '#EEF2FF',
+    marginRight: 8,
+  },
+  todayButtonText: {
+    fontSize: 12,
+    fontWeight: '600',
+    color: '#4C1D95',
+  },
   daysContainer: {
     paddingBottom: 8,
   },