Fix ExampleCommand build break caused by Spectre.Console.Cli API change

[Copilot]

AsyncCommand<T>.ExecuteAsync changed signature in a newer version of Spectre.Console.Cli — the override now requires a CancellationToken parameter and is protected rather than public, breaking the Example project build.

Changes

• Program.cs: Update ExecuteAsync override to match the new signature:

  // Before
  public override async Task<int> ExecuteAsync(CommandContext context, ExampleSettings settings)
  
  // After
  protected override async Task<int> ExecuteAsync(CommandContext context, ExampleSettings settings, CancellationToken cancellationToken)

• ci.yml: Add a dedicated build step for ConsoleMarkdownRenderer.Example so regressions in the example project are caught by CI going forward.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.46%. Comparing base (41e969d) to head (1bc068b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #47   +/-   ##
=======================================
  Coverage   90.46%   90.46%           
=======================================
  Files          18       18           
  Lines         839      839           
  Branches       86       86           
=======================================
  Hits          759      759           
  Misses         59       59           
  Partials       21       21           

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