Build two versions for Fdroid supporting pre-11 phones and newer systems

[mariobehling]

The goal is to ensure that all phones can use the Fdroid store and have a running app.

Issue reported by @drawnto

[froscon2024]

I leave a report from Froscon2025. There was one older person talking with @mariobehling and myself who told us that he would like to use the app. The app was not working on his really old phone.
I told to this person, that there is also sort of a lowest possible Android version that could be used because the Android API have got at a point many years ago the essential functionality to use Bluetooth LE. I think the person had a phone in use that was using a Android version that was older then that. I explained to the person that the Badge is using Bluetooth LE.

The goal should be to add the lowest possible Android version/API version there, where Bluetooth LE functionality have been added. Otherwise this would lead just to issue reports and frustration at the users when they can install and maybe even start the app but the core functionality wont be working.

BTW it would be nice also for such use cases to have inside the app the functionality to use USB mode instead of bluetooth mode to write to the badge. Take a look at for example the Meshtastic app where you can connect your hardware to the phone over cable and also over bluetooth.
Such cable communication mode build into the app would make things possible like to be able to power the badge over USB-OTG cable and also change every few minutes what is been displayed on the badge. Also there are companies and conferences that are more private and forbid the usage of RF-technology. A custom badgemagic firmware with blueooth functionality disabled wont be able to be used with the badgemagic android app at the moment and you would have to use a computer or a postmarketOS phone instead to run the desktop applications on there.

[froscon2024]

Maybe reopen again because commit was reverted: #1361 (reference)