Adds unit tests for SetName activity (#7116)

* Add unit tests for `SetName` activity to validate workflow name assignment and edge case handling

* Remove unused `Elsa.Workflows.Activities` import from `SetNameTests`.

test/unit/Elsa.Activities.UnitTests/Primitives/SetNameTests.cs

@@ -0,0 +1,56 @@
+using Elsa.Testing.Shared;
+using Elsa.Workflows;
+
+namespace Elsa.Activities.UnitTests.Primitives;
+
+public class SetNameTests
+{
+    [Fact(DisplayName = "SetName sets workflow name and completes successfully")]
+    public async Task Should_Set_Workflow_Name_And_Complete()
+    {
+        // Arrange
+        const string name = "My Workflow";
+
+        // Act
+        var context = await ExecuteAsync(name);
+
+        // Assert
+        Assert.Equal(name, context.WorkflowExecutionContext.Name);
+        Assert.Equal(ActivityStatus.Completed, context.Status);
+    }
+
+    [Theory(DisplayName = "SetName handles various name values")]
+    [InlineData("Simple Name")]
+    [InlineData("Name-With-Dashes")]
+    [InlineData("Name_With_Underscores")]
+    [InlineData("Name.With.Dots")]
+    [InlineData("123 Numeric Name")]
+    [InlineData("")]
+    public async Task Should_Handle_Various_Name_Values(string name)
+    {
+        // Act
+        var context = await ExecuteAsync(name);
+
+        // Assert
+        Assert.Equal(name, context.WorkflowExecutionContext.Name);
+    }
+
+    [Fact(DisplayName = "SetName handles null value")]
+    public async Task Should_Handle_Null_Value()
+    {
+        // Act
+        var context = await ExecuteAsync(null!);
+
+        // Assert
+        Assert.Null(context.WorkflowExecutionContext.Name);
+    }
+
+    private static async Task<ActivityExecutionContext> ExecuteAsync(string name)
+    {
+        var setName = new SetName
+        {
+            Value = new(name)
+        };
+        return await new ActivityTestFixture(setName).ExecuteAsync();
+    }
+}