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/SessionUserInfo.cs

@@ -2,26 +2,24 @@
 // Copyright (c) PlaceholderCompany. All rights reserved.
 // </copyright>
 
+namespace MediaBrowser.Model.Session;
 #nullable disable
-using System;
+   using global::System;
 
-namespace MediaBrowser.Model.Session
-{
-    /// <summary>
-    /// Class SessionUserInfo.
-    /// </summary>
-    public class SessionUserInfo
-    {
-        /// <summary>
-        /// Gets or sets the user identifier.
-        /// </summary>
-        /// <value>The user identifier.</value>
-        public Guid UserId { get; set; }
+   /// <summary>
+   /// Class SessionUserInfo.
+   /// </summary>
+   public class SessionUserInfo
+   {
+       /// <summary>
+       /// Gets or sets the user identifier.
+       /// </summary>
+       /// <value>The user identifier.</value>
+       public Guid UserId { get; set; }
 
-        /// <summary>
-        /// Gets or sets the name of the user.
-        /// </summary>
-        /// <value>The name of the user.</value>
-        public string UserName { get; set; }
-    }
-}
+       /// <summary>
+       /// Gets or sets the name of the user.
+       /// </summary>
+       /// <value>The name of the user.</value>
+       public string UserName { get; set; }
+   }