[Feature Request] Update docs and skills to reference Blazor helpers from released Microsoft.Identity.Web package

[jmprieur]

Is your feature request related to a problem? Please describe.
Currently, developers using Blazor Server with .NET Aspire must manually copy BlazorAuthenticationChallengeHandler.cs and LoginLogoutEndpointRouteBuilderExtensions.cs from the .github/skills/entra-id-aspire-authentication/ folder. This is error-prone and creates maintenance burden when the helpers are updated.

Describe the solution you'd like
Once Microsoft.Identity.Web ships with the integrated Blazor helpers (tracked in separate issue), update all documentation and skills to reference the official NuGet package:

• Update .github/skills/entra-id-aspire-authentication/SKILL.md to remove "copy from skill folder" instructions
• Update docs/frameworks/aspire.md to reference the helpers as part of the package
• Ensure sample code shows using Microsoft.Identity.Web; without manual file copies

Describe alternatives you've considered

• Keep the copy-from-skill-folder approach (rejected: maintenance burden, version drift)
• Create a separate NuGet package for Blazor helpers (rejected: adds complexity, no new dependencies needed)

Additional context

• Prerequisite: Microsoft.Identity.Web package with Blazor helpers must be released on NuGet before this issue can be completed
• Related files:
  • .github/skills/entra-id-aspire-authentication/SKILL.md
  • .github/skills/entra-id-aspire-authentication/BlazorAuthenticationChallengeHandler.cs
  • .github/skills/entra-id-aspire-authentication/LoginLogoutEndpointRouteBuilderExtensions.cs
  • docs/frameworks/aspire.md

/cc @jmprieur