docs: mount the host os-release and fix the agent public host after tunnel enrollment [SKIP TESTS]

packaging/compose/agent/compose.yaml

@@ -21,6 +21,7 @@ services:
     network_mode: host
     volumes:
       - ./.data:/etc/monitor
+      - /etc/os-release:/etc/os-release:ro  # 让节点读到宿主机的系统名（镜像里是 Ubuntu）
     read_only: true
     tmpfs:
       - /tmp:rw,noexec,nosuid,size=64m,mode=1777