feat(insta-lab): cutover to Redis push, Playwright 렌더 호출 제거 (SP-4)

_bg_create_slate, _bg_render의 await card_renderer.render_slate(...)
호출을 Redis RPUSH queue:insta-render 로 전환.

NAS는 task_id 발급 + 큐 푸시 + 30~70% 진행률 보고만. Windows insta-render
워커가 BLPOP → 렌더 → webhook으로 succeeded 보고 시 NAS가
update_slate_status('rendered') 트리거.

Plan-B-Insta Phase 3 (cutover).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

insta-lab/app/internal_router.py

@@ -56,6 +56,12 @@ def insta_update(payload: UpdatePayload):
         result_id=result_id,
         error=payload.error,
     )
+    # succeeded 시 slate_status도 'rendered'로 갱신 (cutover 후 NAS가 처리)
+    if payload.status == "succeeded" and result_id is not None:
+        try:
+            db.update_slate_status(result_id, "rendered")
+        except Exception:
+            logger.exception("update_slate_status %s 실패 (무시)", result_id)
     logger.info(
         "internal/insta/update task=%s status=%s progress=%d",
         payload.task_id, payload.status, payload.progress,