fix(queue): migration 117에서 DO $$ BEGIN 제거 (BEGIN 검증 회피)

_validate_sql_content가 PL/pgSQL의 BEGIN을 트랜잭션 제어문으로 오탐.
guard check를 제거하고 CREATE UNIQUE INDEX 자체의 중복 실패에 의존.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

migrations/117_queue_active_unique.sql

@@ -7,30 +7,12 @@ WHERE a.document_id = b.document_id
   AND a.started_at < NOW() - INTERVAL '10 minutes'
   AND b.status = 'pending';
 
--- Step 2: guard check — 활성 중복이 남아있으면 migration 중단
-DO $$
-DECLARE
-  dup_count INTEGER;
-BEGIN
-  SELECT COUNT(*) INTO dup_count
-  FROM (
-    SELECT document_id, stage
-    FROM processing_queue
-    WHERE status IN ('pending', 'processing')
-    GROUP BY document_id, stage
-    HAVING COUNT(*) > 1
-  ) sub;
-
-  IF dup_count > 0 THEN
-    RAISE EXCEPTION 'migration 117 blocked: % active duplicate(s) remain. Run manual cleanup first.', dup_count;
-  END IF;
-END $$;
-
--- Step 3: 기존 constraint 제거
+-- Step 2: 기존 constraint 제거
 ALTER TABLE processing_queue
     DROP CONSTRAINT processing_queue_document_id_stage_status_key;
 
--- Step 4: partial unique index (활성 행은 (document_id, stage)당 최대 1개)
+-- Step 3: partial unique index (활성 행은 (document_id, stage)당 최대 1개)
+-- 활성 중복이 남아있으면 여기서 자연스럽게 실패 → 수동 정리 후 재시도
 CREATE UNIQUE INDEX uq_queue_active
     ON processing_queue (document_id, stage)
     WHERE status IN ('pending', 'processing');