chore(license): relicense artwork and move non-free media out (#3173)

fluxer_desktop/packaging/linux/app.fluxer.Fluxer.metainfo.xml

@@ -44,7 +44,7 @@
     <screenshots>
         <screenshot type="default" xml:lang="en">
             <caption>The main Fluxer window.</caption>
-            <image type="source" width="1920" height="1080">https://raw.githubusercontent.com/fluxerapp/fluxer/refs/heads/main/fluxer_static/marketing/screenshots/desktop-2560w.avif</image>
+            <image type="source" width="2560" height="2227">https://fluxer.app/static/img/screenshots-desktop-2560w.948e9d88f4c9807a.avif</image>
         </screenshot>
     </screenshots>
     <url type="bugtracker">https://github.com/fluxerapp/fluxer/issues</url>