fix:修复更新记录失败的问题

lib/service/health_service.dart

@@ -93,18 +93,19 @@ class HealthService {
 
   Future<bool> updateRecord(HealthRecord record) async {
     try {
-      print(record.date);
-      final existingRecords =
-          box.values.where((item) => item.date == record.date).toList();
+      final existingRecords = box.values.toList();
+      final index = existingRecords.indexWhere((item) => item.date == record.date);
 
-      if (existingRecords.isEmpty) {
-        await addRecord(record);
+      if (index == -1) {
+        await box.add(record);
       } else {
-        await record.save();
+        final key = box.keyAt(index);
+        await box.put(key, record);
       }
+      
       return true;
     } catch (e) {
-      print(e.toString());
+      print('Update record error: $e');
       return false;
     }
   }