chore: import MusifyBackend into monorepo (preserving history)

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

MusifyBackend/Application/Configuration/StreamGatewayConfiguration.cs

@@ -0,0 +1,16 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Musify.Application.Configuration
+{
+    public class StreamGatewayConfiguration
+    {
+        public const string SectionName = "StreamGateway";
+
+        [Url]
+        [Required]
+        public required string PublicBaseUrl { get; set; }
+
+        [Required]
+        public string AudioFileName { get; set; } = "audio.m4a";
+    }
+}