Improve Code Consistency Between RenderMod and RenderManager

UI/RenderButton.cs

@@ -51,7 +51,7 @@ namespace ADOFAIRenderer.UI
         public void OnClick()
         {
             if (IsAnyFieldEmpty()) return;
-            if (RenderMod.IsRendering) return;
+            if (RenderManager.IsActive) return;
 
             if (!double.TryParse(targetFPSInput.text, out var targetFPS) || targetFPS <= 0)
             {