feat: migrate legacy playout workflow and scenes

tests/MBN_STOCK_WEBVIEW.Playout.Tests/PlayoutSceneCompositionFactoryTests.cs

@@ -0,0 +1,53 @@
+using MBN_STOCK_WEBVIEW.Core.Playout.Scenes;
+
+namespace MBN_STOCK_WEBVIEW.Playout.Tests;
+
+public sealed class PlayoutSceneCompositionFactoryTests
+{
+    [Fact]
+    public void Default_MatchesLegacyFadeAndRequiresNoExternalAsset()
+    {
+        var result = PlayoutSceneCompositionFactory.Create(new PlayoutOptions());
+
+        Assert.Equal(6, result.FadeDuration);
+        Assert.Equal(LegacySceneBackgroundKind.None, result.BackgroundKind);
+        Assert.Null(result.BackgroundAssetPath);
+    }
+
+    [Fact]
+    public void TrustedRelativeVideo_IsVerifiedEvenInDryRun()
+    {
+        using var scenes = TemporarySceneDirectory.Create("Video\\studio.vrv");
+        var result = PlayoutSceneCompositionFactory.Create(new PlayoutOptions
+        {
+            Mode = PlayoutMode.DryRun,
+            SceneDirectory = scenes.Path,
+            LegacySceneBackgroundKind = LegacySceneBackgroundKind.Video,
+            LegacySceneBackgroundAssetPath = "Video\\studio.vrv"
+        });
+
+        Assert.Equal(LegacySceneBackgroundKind.Video, result.BackgroundKind);
+        Assert.Equal(Path.Combine("Video", "studio.vrv"), result.BackgroundAssetPath);
+        Assert.Equal(2004, result.BackgroundVideoLoopCount);
+    }
+
+    [Theory]
+    [InlineData("Video:studio.vrv")]
+    [InlineData("..\\outside.vrv")]
+    [InlineData("Video\\missing.vrv")]
+    [InlineData("Video\\studio.exe")]
+    public void InvalidOrMissingBackground_FailsBeforeDryRunPrepare(string relativePath)
+    {
+        using var scenes = TemporarySceneDirectory.Create("Video\\studio.vrv");
+        var options = new PlayoutOptions
+        {
+            Mode = PlayoutMode.DryRun,
+            SceneDirectory = scenes.Path,
+            LegacySceneBackgroundKind = LegacySceneBackgroundKind.Video,
+            LegacySceneBackgroundAssetPath = relativePath
+        };
+
+        Assert.Throws<PlayoutConfigurationException>(() =>
+            PlayoutSceneCompositionFactory.Create(options));
+    }
+}