Screenshare: auto-pick game window, remember Vesktop stream audio

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

hosts/FredOS-Gaming.nix

@@ -6,7 +6,11 @@
       mangohud
       gamescope
       spotify
-      vesktop
+      # Preselect the last stream's audio source (e.g. Hearthstone) when it's
+      # running again, instead of resetting to "None" every Go Live.
+      (vesktop.overrideAttrs (old: {
+        patches = (old.patches or [ ]) ++ [ ../patches/vesktop-remember-stream-audio.patch ];
+      }))
       lsfg-vk
       lsfg-vk-ui
       faugus-launcher