Describe the bug
Major Updater should add an option to perform the update during the next shutdown, instead of restarting into the update process and then restarting again after it completes/fails.
The plan
Add a new page before the update begins ("When should updating begin?") where you can pick between "Next time Feren OS starts", or "Immediately after preparation completes".
On that page, also add the option to "Shut Down instead of restarting Feren OS when preparation finishes"
Depending on the option chosen, supply flags to the Major Updater screen to perform the requested operation-pair after preparation completes
If "Immediately" is selected, after preparation run the Major Updater service, but modified to have the update as its stop job, followed by running either reboot or poweroff depending on options
Otherwise, commence update as normal, running either reboot or poweroff depending on options after preparation completes (the reboot after the update completes will happen irregardless)
Describe the bug Major Updater should add an option to perform the update during the next shutdown, instead of restarting into the update process and then restarting again after it completes/fails.
The plan