• upgrade date/time pickers to @mui/x-date-pickers v6 beta, improving
  time entry. Fixes
  #256.
• systemd integration on Linux
  • notify systemd on starting/stopping. To take advantage of this, you'll
    need to modify your /etc/systemd/moonfire-nvr.service. See
    guide/install.md.
  • socket activation. See ref/config.md.