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/main.py

@@ -1030,7 +1030,12 @@ def create_pipeline(req: PipelineCreate):
 
 @app.get("/api/music/pipeline")
 def list_pipelines_endpoint(status: str = "all"):
-    pipelines = _db_module.list_pipelines(active_only=(status == "active"))
+    if status == "active":
+        pipelines = _db_module.list_pipelines(active_only=True)
+    elif status == "failed":
+        pipelines = _db_module.list_pipelines_by_state("failed")
+    else:
+        pipelines = _db_module.list_pipelines(active_only=False)
     return {"pipelines": pipelines}