feat(insta-lab): wire internal_router + Redis client (SP-4 prep)

main.py에 internal_router include + 모듈 레벨 redis client.
requirements.txt에 redis>=5.0 추가 (playwright 제거는 Task 12에서).

Plan-B-Insta Phase 1 마무리. Task 11에서 _bg_render를 Redis push로 전환.

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

insta-lab/app/main.py

@@ -16,10 +16,18 @@ from .config import (
     INSTA_DATA_PATH, DB_PATH, DEFAULT_CATEGORY_SEEDS, KEYWORDS_PER_CATEGORY,
     INSTA_DEFAULT_THEME,
 )
+import redis.asyncio as aioredis
+
 from . import db, news_collector, keyword_extractor, card_writer, card_renderer, trend_collector
+from .internal_router import router as internal_router
 
 logger = logging.getLogger(__name__)
+
+REDIS_URL = os.getenv("REDIS_URL", "redis://redis:6379")
+redis_client = aioredis.from_url(REDIS_URL, decode_responses=False)
+
 app = FastAPI()
+app.include_router(internal_router)
 
 app.add_middleware(
     CORSMiddleware,