feat(services/insta-render): FastAPI entry + lifespan (SP-3)

lifespan에서 Browser pool init + worker_loop spawn. shutdown 시 정상 cleanup.
GET /health (LivenessProbe용).

Plan-B-Insta Phase 2.

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

services/insta-render/main.py

@@ -0,0 +1,41 @@
+"""insta-render FastAPI entry — health + lifespan (Browser pool + worker loop)."""
+from __future__ import annotations
+
+import asyncio
+import logging
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+
+import card_renderer
+import worker
+
+logging.basicConfig(level=logging.INFO, format="%(asctime)s %(name)s %(levelname)s %(message)s")
+logger = logging.getLogger(__name__)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    # Browser pool 초기화 (Chromium launch)
+    await card_renderer.init_browser()
+    # 큐 워커 백그라운드 시작
+    worker_task = asyncio.create_task(worker.worker_loop())
+    logger.info("insta-render lifespan 시작")
+    try:
+        yield
+    finally:
+        worker_task.cancel()
+        try:
+            await worker_task
+        except asyncio.CancelledError:
+            pass
+        await card_renderer.shutdown_browser()
+        logger.info("insta-render lifespan 종료")
+
+
+app = FastAPI(lifespan=lifespan)
+
+
+@app.get("/health")
+def health():
+    return {"ok": True, "service": "insta-render"}