Suppress non-critical warnings, refactor Emby.Naming

Expanded .editorconfig to silence non-critical IDE/StyleCop warnings and updated Emby.Naming.csproj to prevent warnings-as-errors in Debug. Refactored codebase for modern C# style, removed unused code and unnecessary usings, and fixed formatting and StringComparison issues. Added detailed documentation on code style and warning suppression. Project now builds cleanly with only critical issues surfaced.

Emby.Naming/Video/FileStack.cs

@@ -19,11 +19,11 @@ namespace Emby.Naming.Video
         /// <param name="name">The stack name.</param>
         /// <param name="isDirectory">Whether the stack files are directories.</param>
         /// <param name="files">The stack files.</param>
-        public this.FileStack(string name, bool isDirectory, IReadOnlyList<string> files)
+        public FileStack(string name, bool isDirectory, IReadOnlyList<string> files)
         {
-            this.Name = name;
-            this.IsDirectoryStack = isDirectory;
-            this.Files = files;
+            Name = name;
+            IsDirectoryStack = isDirectory;
+            Files = files;
         }
 
         /// <summary>
@@ -47,7 +47,7 @@ namespace Emby.Naming.Video
         /// <param name="file">Path of desired file.</param>
         /// <param name="isDirectory">Requested type of stack.</param>
         /// <returns>True if file is in the stack.</returns>
-        public bool this.ContainsFile(string file, bool isDirectory)
+        public bool ContainsFile(string file, bool isDirectory)
         {
             if (string.IsNullOrEmpty(file))
             {