chore: import MusifyBackend into monorepo (preserving history)

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

MusifyBackend/Application/Contracts/IPictureService.cs

@@ -0,0 +1,7 @@
+namespace Musify.Application.Contracts
+{
+    public interface IPictureService
+    {
+        Task<Stream> ResizePictureAsWebpAsync(Stream pictureStream, int width, int height, CancellationToken cancellationToken);
+    }
+}