ops: add docker-compose.yml and deploy-postgres.sh for production cutover

- docker-compose.yml: Postgres 16 Alpine on port 5433 with healthcheck
- scripts/deploy-postgres.sh: one-shot deployment script that handles
  container startup, schema creation, npm install, data migration, and
  frontend build
- Backup SQLite database as cve_database.db.pre-postgres-backup

docker-compose.yml

@@ -0,0 +1,26 @@
+# Docker Compose for CVE Dashboard PostgreSQL
+# Run: docker compose up -d
+# Stop: docker compose down
+# View logs: docker compose logs -f postgres
+
+services:
+  postgres:
+    image: postgres:16-alpine
+    container_name: steam-postgres
+    restart: unless-stopped
+    environment:
+      POSTGRES_DB: cve_dashboard
+      POSTGRES_USER: steam
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-sV4xmC9xAUCFop0ypxMVS056QgPqGrX}
+    ports:
+      - "5433:5432"
+    volumes:
+      - steam-pgdata:/var/lib/postgresql/data
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U steam -d cve_dashboard"]
+      interval: 10s
+      timeout: 5s
+      retries: 5
+
+volumes:
+  steam-pgdata: