docs(ranking): 스냅샷 job DDL을 추가한다

docs/20260608_크리에이터_랭킹/create-ranking-tables.sql

@@ -39,3 +39,23 @@ create index idx_creator_ranking_snapshot_replace_period
 
 create index idx_creator_ranking_snapshot_period_creator
     on creator_ranking_snapshot (aggregation_start_at_utc, aggregation_end_at_utc, creator_id);
+
+create table creator_ranking_snapshot_job (
+    id bigint not null auto_increment comment '크리에이터 랭킹 스냅샷 생성 job ID',
+    aggregation_start_at_utc timestamp not null comment '집계 시작 시각(UTC, 포함)',
+    aggregation_end_at_utc timestamp not null comment '집계 종료 시각(UTC, 미포함)',
+    trigger_type varchar(20) not null comment '실행 트리거(SCHEDULED, MANUAL)',
+    status varchar(20) not null comment 'job 상태(PENDING, PROCESSING, DONE, FAILED)',
+    last_error text null comment '마지막 실패 사유',
+    processing_started_at timestamp null comment '처리 시작 시각',
+    processed_at timestamp null comment '처리 완료 시각',
+    created_at timestamp not null default current_timestamp comment '생성 시각',
+    updated_at timestamp not null default current_timestamp on update current_timestamp comment '수정 시각',
+    primary key (id)
+) engine=InnoDB default charset=utf8mb4 comment='크리에이터 랭킹 스냅샷 생성 job 이력';
+
+create index idx_creator_ranking_snapshot_job_period_status
+    on creator_ranking_snapshot_job (aggregation_start_at_utc, aggregation_end_at_utc, status);
+
+create index idx_creator_ranking_snapshot_job_status_created_at
+    on creator_ranking_snapshot_job (status, created_at);