dsh-scrcpy-mirror: Cast Android screen to DSH chat

This is a DSH client plugin maintained by gem-gti that utilizes scrcpy to mirror Android phone screens to Windows PCs. Encapsulated as the `phone_mirror` tool and the `/mirror` session command, it supports status, start, stop, connect, and screenshot. The article introduces core features, four installation methods, typical usage, configuration options, prerequisites, sandbox implementation details, and known limitations, and provides a table of contents and a GitHub link.