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/main.py

@@ -161,12 +161,20 @@ async def _bg_create_slate(task_id: str, keyword: str, category: str, keyword_id
     try:
         db.update_task(task_id, "processing", 30, "카피 생성 중")
         sid = card_writer.write_slate(keyword=keyword, category=category)
-        db.update_task(task_id, "processing", 70, "카드 렌더 중")
-        await card_renderer.render_slate(sid, template=f"{INSTA_DEFAULT_THEME}/card.html.j2")
-        db.update_slate_status(sid, "rendered")
         if keyword_id:
             db.mark_keyword_used(keyword_id)
-        db.update_task(task_id, "succeeded", 100, "완료", result_id=sid)
+        # Redis 큐에 push — Windows insta-render worker가 BLPOP 후 렌더
+        from datetime import datetime, timezone, timedelta
+        kst = timezone(timedelta(hours=9))
+        payload = {
+            "task_id": task_id,
+            "kind": "insta",
+            "params": {"slate_id": sid, "theme": INSTA_DEFAULT_THEME},
+            "submitted_at": datetime.now(kst).isoformat(),
+        }
+        await redis_client.rpush("queue:insta-render", json.dumps(payload))
+        # 사용자는 GET /api/insta/tasks/{task_id}로 폴링 — worker가 webhook으로 status update
+        db.update_task(task_id, "processing", 70, "Redis 큐 푸시 → Windows worker 대기 중", result_id=sid)
     except Exception as e:
         logger.exception("create slate failed")
         db.update_task(task_id, "failed", 0, "", error=str(e))
@@ -200,13 +208,20 @@ def get_slate(slate_id: int):
 
 
 async def _bg_render(task_id: str, slate_id: int):
+    """Redis 큐에 push. 실 렌더는 Windows insta-render worker."""
     try:
-        db.update_task(task_id, "processing", 30, "재렌더 중")
-        await card_renderer.render_slate(slate_id, template=f"{INSTA_DEFAULT_THEME}/card.html.j2")
-        db.update_slate_status(slate_id, "rendered")
-        db.update_task(task_id, "succeeded", 100, "완료", result_id=slate_id)
+        from datetime import datetime, timezone, timedelta
+        kst = timezone(timedelta(hours=9))
+        payload = {
+            "task_id": task_id,
+            "kind": "insta",
+            "params": {"slate_id": slate_id, "theme": INSTA_DEFAULT_THEME},
+            "submitted_at": datetime.now(kst).isoformat(),
+        }
+        await redis_client.rpush("queue:insta-render", json.dumps(payload))
+        db.update_task(task_id, "processing", 30, "Redis 큐 푸시 → Windows worker 대기 중")
     except Exception as e:
-        logger.exception("render failed")
+        logger.exception("queue push failed")
         db.update_task(task_id, "failed", 0, "", error=str(e))