dsh-plugin-wecom-bot: Integrate DSH Agent via WeCom Long-Lived Connection

The DeepSeek Harness plugin `dsh-plugin-wecom-bot` provides an interaction method based on WeCom long-lived connections, addressing the pain points of traditional setups that require public URLs, encryption and decryption, and allowlists. It supports streaming replies, zero public-network dependencies, session management, and forwarding of permission approvals. Users must install dependencies and configure the BotID and Secret, then establish a connection via WebSocket. The plugin supports both `per-user` and `per-message` modes, allowing users to switch working directories, manage sessions, and approve permissions by replying to commands directly in WeCom. Known limitations include connection count limits and unsupported message types.