Help install 3m-ui (Mihomo server Web panel) on a Linux VPS as root.

Requirements:
1. Use only the official one-liner — do not change the URL, add unknown flags, or swap in third-party mirrors:
   curl -fsSL https://raw.githubusercontent.com/kazeyukiro/3m-ui/main/scripts/install.sh | sudo sh
2. Before install: confirm CPU arch (full bundle needs amd64 or arm64), init system (systemd or OpenRC), GitHub reachability, and that the firewall can open the panel port (default 8080) plus later node ports.
3. After install:
   - Save the one-time admin password printed in the terminal (it is not shown again; run `sudo 3m-ui reset-admin` if lost)
   - Confirm the service with `systemctl status 3m-ui` (or equivalent)
   - Explain how to reach http://SERVER_IP:8080/ and that the password must be changed on first login
4. Common ops: `sudo 3m-ui status | update | logs | restart | backup`
5. Docs: https://3m-ui.top/docs/ and https://github.com/kazeyukiro/3m-ui
6. Do not wipe existing /etc/3m-ui or /var/lib/3m-ui; prefer `sudo 3m-ui update` for upgrades.
If a step fails, troubleshoot from the error output; do not invent or switch to unofficial install sources.
