fix(printer):修复打印机选择逻辑并优化查询

- 调整打印机选择逻辑，确保正确获取打印机ID
- 优化SourceMapper查询，按创建时间倒序并限制结果数量- 修复可能因逻辑错误导致的打印机选择异常问题

src/main/resources/mapper/SourceMapper.xml

@@ -358,5 +358,7 @@
         select *
         from source
         where face_sample_id = #{faceSampleId} and type = #{type}
+        order by create_time desc
+        limit 1
     </select>
 </mapper>