fix: ensure backfill_state table is created inside backward_backfill.py initialization

crawler/backward_backfill.py

@@ -47,6 +47,17 @@ def init_backfill_states(yesterday_str: str):
     with get_db_connection() as conn:
         cursor = conn.cursor()
         
+        # 테이블 자동 생성
+        cursor.execute("""
+            CREATE TABLE IF NOT EXISTS backfill_state (
+                site_id TEXT PRIMARY KEY,
+                last_backfilled_date TEXT,
+                consecutive_zero_count INTEGER DEFAULT 0,
+                status TEXT DEFAULT 'RUNNING'
+            );
+        """)
+        conn.commit()
+        
         # NREMS 분할 호기도 식별 가능하게 리스트 빌드
         site_ids = []
         for p in plants: