优化目录结构

backend/src/main/java/com/openisle/model/Draft.java

@@ -0,0 +1,41 @@
+package com.openisle.model;
+
+import jakarta.persistence.*;
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import lombok.Setter;
+
+import java.util.HashSet;
+import java.util.Set;
+
+@Entity
+@Getter
+@Setter
+@NoArgsConstructor
+@Table(name = "drafts", uniqueConstraints = {
+        @UniqueConstraint(columnNames = {"author_id"})
+})
+public class Draft {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    private String title;
+
+    @Column(columnDefinition = "TEXT")
+    private String content;
+
+    @ManyToOne(fetch = FetchType.LAZY, optional = false)
+    @JoinColumn(name = "author_id")
+    private User author;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "category_id")
+    private Category category;
+
+    @ManyToMany(fetch = FetchType.LAZY)
+    @JoinTable(name = "draft_tags",
+            joinColumns = @JoinColumn(name = "draft_id"),
+            inverseJoinColumns = @JoinColumn(name = "tag_id"))
+    private Set<Tag> tags = new HashSet<>();
+}