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.

MediaBrowser.Model/Session/PlaystateRequest.cs

@@ -4,18 +4,16 @@
 
 #pragma warning disable CS1591
 
-namespace MediaBrowser.Model.Session
-{
-    public class PlaystateRequest
-    {
-        public PlaystateCommand Command { get; set; }
+namespace MediaBrowser.Model.Session;
+   public class PlaystateRequest
+   {
+       public PlaystateCommand Command { get; set; }
 
-        public long? SeekPositionTicks { get; set; }
+       public long? SeekPositionTicks { get; set; }
 
-        /// <summary>
-        /// Gets or sets the controlling user identifier.
-        /// </summary>
-        /// <value>The controlling user identifier.</value>
-        public string? ControllingUserId { get; set; }
-    }
-}
+       /// <summary>
+       /// Gets or sets the controlling user identifier.
+       /// </summary>
+       /// <value>The controlling user identifier.</value>
+       public string? ControllingUserId { get; set; }
+   }