v4.5.2

Fleet stops polling when the sidebar is collapsed on This Mac. 4.5.1 polled
whenever the window was on screen, but with the Devices sidebar collapsed and This
Mac selected, no fleet data is shown anywhere — and the machines were still polled
every 3 s. Now they are polled only while something shows them: the sidebar (each
row is a machine's live summary), the Fleet overview, or a machine's page. Collapse
the sidebar on This Mac and every agent connection closes; open it, or switch to
Fleet, and polling resumes at once, with a break in the charts for the time in
between. (#71)