chore(assets): refresh screenshots, store graphics and Steam hero

- Add new desktop and iOS screenshots under assets/screenshots, named by screen, theme and form factor, and optimized with pngquant + oxipng
- Add feature graphics under assets/feature-graphics: Play Store feature graphic, README hero and mobile strip, and phone/desktop store shots
- Use them in the README, Flathub metainfo (plain screenshots) and F-Droid metadata (phone screenshots + featureGraphic)
- Replace the Steam library hero with one made from the new UI
- Remove the old desktop and mobile screenshots

README.md

@@ -16,9 +16,9 @@ Bring your own music metadata/playlist/audio-source with plugins created by comm
 
 ---
 
-![Spotube Desktop](assets/branding/spotube-screenshot.png)
+![Spotube Desktop](assets/feature-graphics/readme-hero.png)
 
-![Spotube Mobile](assets/branding/mobile-screenshots/combined.jpg)
+![Spotube Mobile](assets/feature-graphics/readme-mobile.png)
 
 </div>
 

packaging/linux/org.spotube.spotube.metainfo.xml.mustache

@@ -55,8 +55,28 @@
 
   <screenshots>
     <screenshot type="default">
-      <caption>Spotube on the desktop</caption>
+      <caption>Browse music from the service your plugin connects to</caption>
-      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/branding/spotube-screenshot.png</image>
+      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/screenshots/home-desktop-dark.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Synced lyrics</caption>
+      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/screenshots/lyrics-desktop-dark.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Your playlists</caption>
+      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/screenshots/playlists-desktop-dark.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Search tracks, albums, artists, playlists and users</caption>
+      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/screenshots/search-desktop-dark.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Local folders and downloads</caption>
+      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/screenshots/local-tracks-desktop-dark.png</image>
+    </screenshot>
+    <screenshot>
+      <caption>Group Jam rooms</caption>
+      <image>https://raw.githubusercontent.com/team-spotube/spotube/master/assets/screenshots/group-jam-desktop-dark.png</image>
     </screenshot>
   </screenshots>