feat(video-render): main.py + services/docker-compose entry (SP-7)

FastAPI lifespan에서 worker_loop 스폰. /health endpoint.
docker-compose: port 18712, NAS_BASE_URL default=18801 (video-lab),
4 provider env (OPENAI_API_KEY, GOOGLE_*, PIAPI_API_KEY, SEEDANCE_API_KEY),
GCP service account JSON read-only mount.
Plan-B-Video Phase 2 완료 — 박재오 머신에서 .env + GCP JSON 작성 + 빌드 대기.

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

services/docker-compose.yml

@@ -49,3 +49,33 @@ services:
       interval: 60s
       timeout: 5s
       retries: 3
+
+  video-render:
+    build:
+      context: ./video-render
+    container_name: video-render
+    restart: unless-stopped
+    ports:
+      - "18712:8000"
+    environment:
+      - TZ=Asia/Seoul
+      - REDIS_URL=${REDIS_URL:-redis://192.168.45.54:6379}
+      - NAS_BASE_URL=${NAS_BASE_URL:-http://192.168.45.54:18801}
+      - INTERNAL_API_KEY=${INTERNAL_API_KEY:-}
+      - OPENAI_API_KEY=${OPENAI_API_KEY:-}
+      - GOOGLE_PROJECT_ID=${GOOGLE_PROJECT_ID:-}
+      - GOOGLE_LOCATION=${GOOGLE_LOCATION:-us-central1}
+      - GOOGLE_GCS_BUCKET=${GOOGLE_GCS_BUCKET:-}
+      - GOOGLE_APPLICATION_CREDENTIALS=/app/keys/gcp-sa.json
+      - PIAPI_API_KEY=${PIAPI_API_KEY:-}
+      - SEEDANCE_API_KEY=${SEEDANCE_API_KEY:-}
+      - VIDEO_MEDIA_ROOT=${VIDEO_MEDIA_ROOT:-/mnt/nas/webpage/data/video}
+      - VIDEO_MEDIA_URL_PREFIX=${VIDEO_MEDIA_URL_PREFIX:-/media/video}
+    volumes:
+      - /mnt/nas/webpage/data/video:/mnt/nas/webpage/data/video
+      - ${GCP_SA_JSON_HOST_PATH:-/etc/webai/gcp-sa.json}:/app/keys/gcp-sa.json:ro
+    healthcheck:
+      test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')"]
+      interval: 60s
+      timeout: 5s
+      retries: 3