Refactor: standardize namespace and using directive style

Refactored all C# test files to use explicit namespace declarations and moved all using directives inside the namespace block for consistency. Updated assembly info and cache files to reflect the new build. Adjusted MvcTestingAppManifest.json to use fully qualified assembly names. No functional changes; all updates are related to code style, organization, and project metadata.

tests/Jellyfin.Naming.Tests/Video/CleanStringTests.cs

@@ -2,12 +2,12 @@
 // Copyright (c) PlaceholderCompany. All rights reserved.
 // </copyright>
 
-using Emby.Naming.Common;
-using Emby.Naming.Video;
-using Xunit;
-
 namespace Jellyfin.Naming.Tests.Video
 {
+    using Emby.Naming.Common;
+    using Emby.Naming.Video;
+    using Xunit;
+
     public sealed class CleanStringTests
     {
         private readonly NamingOptions _namingOptions = new NamingOptions();