flutter takes color-scheme instead of theme

[denisok]

Setup fluffychat from flathub and found that it is in a light theme. This should fix it, as well as maybe help other applications.

• https://gitlab.com/famedly/fluffychat/-/issues/1111#note_1324504258
• https://wiki.archlinux.org/title/Dark_mode_switching#gsettings

[FilippoBonazziSUSE]

Nice one. I don't have fluffychat, but I have tested this and it seems to work in the general case as well.

For example, I have nautilus installed and I had never paid attention to the fact that it had the light theme. This one-liner switched it to dark.