refactor : PostLike 엔터티 구현, Member엔터티 및 Post엔터티와 단방향 연관관계 설정, N:1

BE/school/src/main/java/thisisus/school/post/domain/PostLike.java

@@ -0,0 +1,26 @@
+package thisisus.school.post.domain;
+
+import lombok.*;
+import thisisus.school.member.domain.Member;
+
+import javax.persistence.*;
+
+@Entity
+@Builder
+@Getter
+@AllArgsConstructor
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+public class PostLike {
+    @Id
+    @GeneratedValue
+    @Column(name = "post_like_id")
+    private long id;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "post_id")
+    private Post post;
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "member_id")
+    private Member member;
+}