chore: import MusifyBackend into monorepo (preserving history)

git-subtree-dir: MusifyBackend
git-subtree-mainline: 6829e769ed
git-subtree-split: ed7b00c2cc

MusifyBackend/Application/Events/UpdatePlayListPictureSourceEvent.cs

@@ -0,0 +1,14 @@
+using Musify.Application.Shared;
+
+namespace Musify.Application.Events
+{
+    public record UpdatePlayListPictureSourceEvent(
+        Guid PlayListId,
+        Guid PictureIntentId,
+        string Bucket,
+        string PictureSourceKey,
+        string PictureDestinationKey,
+        ImageSize Small,
+        ImageSize Medium,
+        ImageSize Large);
+}