chore(infra): packs-lab 서비스 통합 (compose 18950 + nginx 5GB streaming + env 7개)

- docker-compose.yml: 포트 18910→18950 수정, env 형식을 list 스타일로 통일,
  TZ/UPLOAD_TOKEN_TTL_SEC 추가, volume 경로를 /app/data/packs으로 정정
- .env.example: packs-lab 섹션 신규 추가 (DSM_HOST/DSM_USER/DSM_PASS/
  BACKEND_HMAC_SECRET/SUPABASE_URL/SUPABASE_SERVICE_KEY/UPLOAD_TOKEN_TTL_SEC/PACK_DATA_PATH)
- nginx/default.conf: 이전 커밋(9a0bbec)에 이미 포함 — 변경 없음

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -181,16 +181,18 @@ services:
     container_name: packs-lab
     restart: unless-stopped
     ports:
-      - "18910:8000"
+      - "18950:8000"
     environment:
-      DSM_HOST: ${DSM_HOST}
-      DSM_USER: ${DSM_USER}
-      DSM_PASS: ${DSM_PASS}
-      BACKEND_HMAC_SECRET: ${BACKEND_HMAC_SECRET}
-      SUPABASE_URL: ${SUPABASE_URL}
-      SUPABASE_SERVICE_KEY: ${SUPABASE_SERVICE_KEY}
+      - TZ=${TZ:-Asia/Seoul}
+      - DSM_HOST=${DSM_HOST:-}
+      - DSM_USER=${DSM_USER:-}
+      - DSM_PASS=${DSM_PASS:-}
+      - BACKEND_HMAC_SECRET=${BACKEND_HMAC_SECRET:-}
+      - SUPABASE_URL=${SUPABASE_URL:-}
+      - SUPABASE_SERVICE_KEY=${SUPABASE_SERVICE_KEY:-}
+      - UPLOAD_TOKEN_TTL_SEC=${UPLOAD_TOKEN_TTL_SEC:-1800}
     volumes:
-      - ${RUNTIME_PATH:-.}/media/packs:/volume1/docker/webpage/media/packs
+      - ${PACK_DATA_PATH:-./data/packs}:/app/data/packs
     healthcheck:
       test: ["CMD", "python", "-c", "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')"]
       interval: 30s