feat: add signed PostgreSQL release updates

oa-backend/src/main/java/com/kaidi/oa/domain/Meeting.java

@@ -5,7 +5,6 @@ import jakarta.persistence.Entity;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
-import jakarta.persistence.Lob;
 import jakarta.persistence.Table;
 
 import java.time.Instant;
@@ -51,7 +50,6 @@ public class Meeting {
     private String description;
 
     /** 会议附件名列表的 JSON（["文件名1","文件名2"]，仅记录文件名，不存二进制）。 */
-    @Lob
     @Column(columnDefinition = "TEXT")
     private String attachmentJson;