Refactor UI config access and clean up code

Use ConfigTextManager instance methods for window sizes and grid heights in both desktop clients. Standardize formatting and remove redundant imports and casts across the Web API and tests.

v2rayN/v2rayN.WebAPI/Launcher/WebLauncher.cs

@@ -1,7 +1,6 @@
 using System.Diagnostics;
-using System.Net.Http;
-using System.Net.Sockets;
 using System.Runtime.InteropServices;
+
 namespace v2rayN.WebAPI.Launcher;
 
 public interface IWebHealthProbe
@@ -312,7 +311,10 @@ public sealed class WebLauncher
             processPath,
             WebReplacementCommand.GetManagedEntryPoint(processPath, commandLine),
             hostArguments);
-        if (command is null) return null;
+        if (command is null)
+        {
+            return null;
+        }
 
         try
         {