[Feature request]: Download and apply updates immediately (for automatic updates)

Hi

Currently, in the Update Manager / Preferences / Automation section, you can enable automatic system + Flatpaks + Applet updates.

I don't know what the logic of these settings is currently (you can only set the repository polling interval on the Options tab), but there is a computer usage scenario in which they are not performed or are performed with a long delay (several days):
I take care of several machines. Several of these machines are turned on for very short periods of time (for example, 10 - 30 minutes) to do some work and the computer is turned off. In this case, the computer will only have time to check for updates (I set Auto-Refresh to 2 minutes after starting), but it will never have time to apply them.

I suggest adding a toggle to the Automation section "Download and apply updates immediately as soon as they are available"

For added clarity and taste, also add a new update icon in the panel area: There is now an update available icon (with a red dot). Add an icon with a green dot symbolizing "updates done" (if done in automatic mode)

Cheers!

Start in Update Manager's Preferences > Automation and Options areas by tracing the existing automatic update and repository polling behavior. Check how the panel's red-dot update icon is selected; done should include an immediate-application toggle and a green-dot status icon when automatic updates complete.