修复测算记录重复保存问题

问题分析：
- 用户测算一次可能产生多条重复记录
- 原因：没有去重机制，每次调用保存接口都创建新记录

解决方案：
- 后端添加去重逻辑：DeductRecordService.saveRecord()
- 根据userId + type + inputData判断是否已存在相同记录
- 如果存在则更新记录，不存在则创建新记录
- 新增Repository方法：findByUserIdAndTypeAndInputData()

去重机制：
- 相同用户、相同测算类型、相同输入数据视为重复
- 重复记录只更新结果数据和AI分析
- 避免数据库中产生大量重复记录

src/main/java/xuan/repository/DeductRecordRepository.java

@@ -29,4 +29,6 @@ public interface DeductRecordRepository extends JpaRepository<DeductRecord, Long
     
     @Query("SELECT d FROM DeductRecord d WHERE d.userId = :userId AND d.type = :type AND (d.name LIKE %:keyword% OR d.occupy LIKE %:keyword%) ORDER BY d.createTime DESC")
     Page<DeductRecord> findByUserIdAndTypeAndKeyword(@Param("userId") String userId, @Param("type") String type, @Param("keyword") String keyword, Pageable pageable);
+    
+    List<DeductRecord> findByUserIdAndTypeAndInputData(String userId, String type, String inputData);
 }

src/main/java/xuan/service/DeductRecordService.java

@@ -20,6 +20,21 @@ public class DeductRecordService {
     
     @Transactional
     public DeductRecord saveRecord(DeductRecord record) {
+        if (record.getInputData() != null && !record.getInputData().isEmpty()) {
+            List<DeductRecord> existingRecords = recordRepository.findByUserIdAndTypeAndInputData(
+                record.getUserId(), 
+                record.getType(), 
+                record.getInputData()
+            );
+            
+            if (!existingRecords.isEmpty()) {
+                DeductRecord existingRecord = existingRecords.get(0);
+                existingRecord.setResultData(record.getResultData());
+                existingRecord.setAiAnalysis(record.getAiAnalysis());
+                return recordRepository.save(existingRecord);
+            }
+        }
+        
         return recordRepository.save(record);
     }