fix: 추천 포스트 URL 길이 수정 및 FK 네임 변경

#1397

Author: nuyh99

backend/src/main/resources/db/migration/prod/V4__alter_table_keyword_reference.sql

@@ -3,8 +3,8 @@ drop table prolog.keyword_reference;
 create table if not exists prolog.recommended_post
 (
     id         bigint auto_increment primary key,
-    url        varchar(255) not null,
+    url        varchar(512) not null,
     keyword_id bigint       not null,
-    constraint FK_KEYWORD_ID
+    constraint FK_RECOMMENDED_POST_PARENT_KEYWORD_ID
         foreign key (keyword_id) references prolog.keyword (id)
 );