feat(agent-office): service_proxy pipeline_retry/list_failed_pipelines (+ music-lab status=failed 필터)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

music-lab/app/db.py

@@ -1135,6 +1135,21 @@ def list_pipelines(active_only: bool = False) -> List[Dict[str, Any]]:
     return [_parse_pipeline_row(r) for r in rows]
 
 
+def list_pipelines_by_state(state: str) -> List[Dict[str, Any]]:
+    """특정 state의 파이프라인만 조회 (예: 'failed')."""
+    sql = """
+        SELECT vp.*, ml.title AS track_title, cj.title AS compile_title
+        FROM video_pipelines vp
+        LEFT JOIN music_library ml ON ml.id = vp.track_id
+        LEFT JOIN compile_jobs cj ON cj.id = vp.compile_job_id
+        WHERE vp.state = ?
+        ORDER BY vp.created_at DESC
+    """
+    with _conn() as conn:
+        rows = conn.execute(sql, (state,)).fetchall()
+    return [_parse_pipeline_row(r) for r in rows]
+
+
 def increment_feedback_count(pid: int, step: str) -> int:
     """원자적으로 feedback_count_per_step.<step>를 +1 한 뒤 새 값을 반환.