dsh-tailscale-sync: Continue Your Desktop DeepSeek Harness Work on a Phone with Zero Configuration

By default, DeepSeek Harness listens locally only, and remote access requires SSH or port forwarding configuration. The `dsh-tailscale-sync` plugin uses a Tailscale encrypted tunnel to enable zero-configuration, secure cross-device access. This plugin ensures that only devices within the same Tailnet can access the web service by implementing port locking, automatic trust for MagicDNS domains, and automatic configuration of a fence. After installation, starting the tunnel with `tailscale serve` allows secure access to Harness from a mobile device via `<machine name>.ts.net`.