Add UWP WAM raw API link alongside MSAL.NET row

Addresses the 404 at /windows/security/identity-protection/web-account-manager/
by linking the live UWP WAM conceptual page at /windows/uwp/security/web-account-manager.
Added as a companion row to the MSAL.NET table, distinguishing high-level (MSAL) from
low-level (WinRT Windows.Security.Authentication.Web.Core).

Co-authored-by: Copilot <[email protected]>

Author: GrantMeStrength

hub/apps/develop/security/index.md

@@ -31,6 +31,7 @@ For apps that need users to sign in with a **Microsoft account or Entra ID (work
 | [Acquire tokens using WAM](https://learn.microsoft.com/en-us/entra/msal/dotnet/acquiring-tokens/desktop-mobile/wam) | Learn how to use MSAL.NET with the WAM broker to acquire tokens for Microsoft and Entra ID accounts in desktop apps including WPF, WinForms, and WinUI 3. |
 | [MSAL.NET overview](https://learn.microsoft.com/en-us/entra/msal/dotnet/) | Overview of the Microsoft Authentication Library for .NET — the recommended library for authentication with Microsoft identity in desktop apps. |
 | [Register an application with the Microsoft identity platform](https://learn.microsoft.com/en-us/entra/identity-platform/quickstart-register-app) | How to register your app in the Azure portal to get a client ID, which is required before using MSAL. |
+| [Web Account Manager (WinRT API)](https://learn.microsoft.com/en-us/windows/uwp/security/web-account-manager) | The underlying WinRT API that WAM is built on (`Windows.Security.Authentication.Web.Core`). Reference this if you need low-level token broker access without MSAL.NET. |
 | [Retrieve a window handle (HWND)](../ui-input/retrieve-hwnd.md) | WAM requires your app's window handle (HWND) to display authentication UI. This article shows how to retrieve it in WPF, WinForms, and WinUI 3. |
 
 > [!NOTE]