File sync sessions count as workspace activity

Coder Desktop file sync sessions communicate with the workspace over SSH, even when both sides of the file sync are idle. I realised this when my workspace hadn't autostopped for over two weeks due to a file sync session I had configured to it on my laptop.

I think it's reasonable to assume that someone using file sync will also have some other connection to their workspace (IDE, SSH) that would bump workspace activity whilst it's actually in use.
One way to fix this might be to modify Mutagen to populate an environment variable over SSH, and then update the Coder agent to not count SSH sessions with that environment variable as authentic activity.

Beginne damit nachzuverfolgen, wie Coder Desktop- und Mutagen-file-sync-SSH-Sitzungen als Workspace-Aktivität gezählt werden, und untersuche dann, wie der Coder agent SSH-Umgebungsvariablen empfängt. Bestätige, dass inaktive file-sync-Sitzungen autostop nicht mehr verhindern, während IDE- oder interaktive SSH-Verbindungen weiterhin als Aktivität zählen.

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