Add localhost setup feedback and remove UI issues (#587)

Author: hvesuk

MCPForUnity/Editor/Windows/Components/Common.uss

@@ -437,6 +437,11 @@
     margin-bottom: 4px;
 }
 
+.help-text.error {
+    color: rgba(255, 80, 80, 1);
+    -unity-font-style: bold;
+}
+
 .path-override-controls {
     flex-direction: row;
     align-items: center;

MCPForUnity/Editor/Windows/Components/Connection/McpConnectionSection.cs

@@ -435,16 +435,24 @@ public void UpdateHttpServerCommandDisplay()
 
             if (!isLocalHttpUrl)
             {
-                httpServerCommandField.value = string.Empty;
-                httpServerCommandField.tooltip = string.Empty;
+                httpServerCommandField.value = "<Invalid Localhost URL>";
+                httpServerCommandField.tooltip = "The command cannot be generated because the URL is not a local address.";
+                httpServerCommandSection.EnableInClassList("invalid-url", true);
                 if (httpServerCommandHint != null)
                 {
-                    httpServerCommandHint.text = "HTTP Local requires a localhost URL (localhost/127.0.0.1/0.0.0.0/::1).";
+                    httpServerCommandHint.text = "⚠ HTTP Local requires a localhost URL (localhost/127.0.0.1/0.0.0.0/::1).";
+                    httpServerCommandHint.AddToClassList("error");
                 }
                 copyHttpServerCommandButton?.SetEnabled(false);
                 return;
             }
 
+            httpServerCommandSection.EnableInClassList("invalid-url", false);
+            if (httpServerCommandHint != null)
+            {
+                httpServerCommandHint.RemoveFromClassList("error");
+            }
+
             if (MCPServiceLocator.Server.TryGetLocalHttpServerCommand(out var command, out var error))
             {
                 httpServerCommandField.value = command;