Refactor Publication class to use JOINED inheritance strategy and IDENTITY generation type

hibernate-project/src/main/java/com/humanbooster/model/Publication.java

@@ -5,12 +5,12 @@ import jakarta.persistence.*;
 import java.time.LocalDate;
 
 @Entity
-@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
+@Inheritance(strategy = InheritanceType.JOINED)
 @DiscriminatorColumn
 public abstract class Publication {
 
     @Id
-    @GeneratedValue(strategy = GenerationType.AUTO)
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
     @Column(nullable = false, length = 200)