Update the app on a regular basis (even without a new stable version released)

This is something I've been thinking about for a while. RetroArch Flatpak build includes by default several assets, such as shaders, controller profiles, core info files, etc. This means that unless the user manually changes the directories and then uses the Online Updater, these assets will only be updated when a new stable version is released, which has been taking several months lately.

I think it would be a good practice to update RetroArch Flatpak on a regular basis, even if a new stable version hasn't been released, to ensure that the users will have the latest assets from time to time.

Updating it more than once a month can be a bit annoying, but at least once every two months could be enough.

Just as additional info, looking at the buildbot back in 2023 there were only two stable releases in the entire year, in 2024 three stable releases, and this year so far only one last January. Personally, I prefer this pace than the one in 2022 which had *nine stable releases* during that year, but it would be nice to have the assets updated more frequently that only two or three times a year.

Of course, I can just manually change directories and then use Online Updater to have the latest assets whenever I want, but this suggestion is just to improve the overall experience for all users out of the box.

Start by reviewing the Flatpak packaging and release process, especially how bundled shaders, controller profiles, and core info files are included. Determine whether periodic builds can update these assets without a new stable RetroArch release; done means an agreed recurring update process is implemented and verified for users.

Written by the indexing model from the issue text.