/**
 * Start a tunnel via expose.sh using SSH.
 *
 * expose.sh requires:
 *  - SSH client installed (built-in on Windows 10+, macOS, Linux)
 *  - SSH keys added to your GitHub account
 *  - Star the repo https://github.com/gaetanlhf/EXPOSE
 *
 * The `sshkey` parameter specifies which SSH private key to use.
 * Can be a full path or just the key name (e.g. "id_personal" → ~/.ssh/id_personal).
 *
 * The `subdomain` parameter is the GitHub username for authentication.
 * expose.sh uses it to verify SSH keys and stargazer status.
 * URL will be: https://<subdomain>.expos.es
 */
export declare function startExposeTunnel(port: number, subdomain?: string, sshkey?: string): Promise<string>;