kilbertert/dsh-herdr

Adds a Herdr panel to the DSH sidebar that opens a host PTY running the `herdr` command and renders it with xterm.js. The connection list comes from the plugin config (`connections`, or the flat `remote`/`session`/`command` keys; with no config it runs plain `herdr`), so the panel can point at any machine. The startup command is typed once per terminal, so switching panels or reloading the page does not open a second session. Requires the Herdr CLI on the machine running DSH.