dsh-lan: DSH LAN Exposure and Balance Query Plugin

`dsh-lan` is a DeepSeek Harness (DSH) plugin designed to address the security risks associated with Web runtimes bound only to the local loopback address and API key exposure. It enables LAN access by changing the bind address to `0.0.0.0` and provides a local RPC interface for scripts to securely query balances without uploading the API key. Installation requires editing the configuration file; once started, it can be used within a trusted network.