.Net: Fix DebuggerDisplay attribute to reference existing property

[Copilot]

Motivation and Context

The [DebuggerDisplay] attribute on AIAgent referenced DisplayName, which was removed in PR #2758. This caused CS0103 compile errors in the debugger visualizer.

Description

Updated [DebuggerDisplay("{DisplayName,nq}")] to [DebuggerDisplay("{Name,nq}")] in AIAgent.cs. The Name property serves the same purpose as a human-readable identifier for debugging.

Changed:

- [DebuggerDisplay("{DisplayName,nq}")]
+ [DebuggerDisplay("{Name,nq}")]
  public abstract class AIAgent

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>.NET: [Bug]: Debugger visualizer for AIAgent throws an error</issue_title>
<issue_description>### Description

I have added an AIAgent to the HostBuilder:

builder.Services.AddAIAgent("Default", "You are a helpful assistant");

When I enter debug mode and hover the mouse over an AIAgent variable, the Debugger visualizer for the AIAgent class shows the error CS0103: The name 'DisplayName' does not exist in the current context:

Package Versions

Microsoft.Agents.AI.Hosting: 1.0.0-preview.260108.1, Microsoft.Agents.AI.OpenAI: 1.0.0-preview.260108.1

.NET Version

.NET 10</issue_description>

<agent_instructions>DisplayName property was intentionally removed from the AIAgent in the PR #2758.
Given that I need to fix this issue by updating the attribute [DebuggerDisplay("{DisplayName,nq}")] on the AIAgent class.
</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes .NET: [Bug]: Debugger visualizer for AIAgent throws an error #3253

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

[Copilot]

Pull request overview

This PR fixes a debugger visualizer error in the AIAgent class by updating the DebuggerDisplay attribute to reference the existing Name property instead of the removed DisplayName property. The DisplayName property was removed in PR #2758, causing CS0103 compile errors when inspecting AIAgent instances in the debugger.

Changes:

• Updated DebuggerDisplay attribute from {DisplayName,nq} to {Name,nq} in AIAgent.cs