[Request] Adding .circ file handeling support

First of all, thanks for distributing this flatpak! It makes my live quite a bit easier.
For now I have to manually configure the app to be able to open .circ files when they are double clicked, could automatic support for this be added?

No file or test is named in the issue. Start by locating the repository's Flatpak metadata and the app's desktop integration settings, then verify how file associations are declared; the work is done when .circ files open in the app from a file manager without manual configuration.

Written by the indexing model from the issue text.