feat(tess): add configurable Pi interaction service (#728)

packages/mosaic/framework/systemd/user/mosaic-interaction-agent@.service

@@ -0,0 +1,17 @@
+[Unit]
+Description=Mosaic operator interaction agent %i
+Documentation=https://git.mosaicstack.dev/mosaicstack/stack
+Requires=mosaic-tmux-holder.service
+After=mosaic-tmux-holder.service
+PartOf=mosaic-tmux-holder.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+Environment=MOSAIC_AGENT_NAME=%i
+EnvironmentFile=%h/.config/mosaic/fleet/agents/%i.env
+ExecStart=/bin/bash %h/.config/mosaic/tools/fleet/start-interaction-service.sh %i
+ExecStop=-/bin/bash -lc 'if [ -n "${MOSAIC_TMUX_SOCKET:-}" ]; then tmux -L "$MOSAIC_TMUX_SOCKET" kill-session -t "=%i"; else tmux kill-session -t "=%i"; fi'
+
+[Install]
+WantedBy=default.target