fix: add debugger display and custom ToString to SwapStyleBuilder

Author: egil

src/Htmxor/Http/SwapStyleBuilder.cs

@@ -1,12 +1,14 @@
 using System.Collections;
 using System.Collections.Specialized;
+using System.Diagnostics;
 using System.Numerics;
 
 namespace Htmxor.Http;
 
 /// <summary>
 /// A builder class for constructing a swap style command string for HTMX responses.
 /// </summary>
+[DebuggerDisplay("{ToString(),nq}")]
 public sealed class SwapStyleBuilder
 {
     private readonly SwapStyle style;
@@ -311,6 +313,17 @@ public SwapStyleBuilder ShowNone()
         return this;
     }
 
+    /// <inheritdoc/>
+    public override string ToString()
+    {
+        var (swapStyle, modifier) = Build();
+        var style = swapStyle.ToHtmxString();
+        var value = !string.IsNullOrWhiteSpace(modifier)
+            ? $"{style} {modifier}"
+            : style;
+        return value;
+    }
+
     /// <summary>
     /// Builds the swap style command string with all specified modifiers.
     /// </summary>