Move to Cratis.Arc.Screenplay 21.14.2 - #69

One line of Directory.Packages.props. Measured on Ada — a real 241-slice application, 3,081 files — by generating with each version from the same checkout and validating the result:

Both PLAY0191 said Read model 'UserAccessPolicy' is built more than once. Studio will not parse a document with errors, so the whole generate → import path stopped at the door — this was the only thing blocking it.

The upstream fix is Arc PR #2546: ArtifactCatalog walked every nested type, so a projection declared inside a specification to assert something about the real projection's contract was captured as though the application shipped it. Two of those in Ada each gave UserAccessPolicy an extra builder.

On the version choice: Cratis.Arc.Screenplay versions cannot be picked by order — some 21.x still require Cratis.Screenplay 1.x. 21.14.2's nuspec declares Cratis.Screenplay 2.1.0, which is what this repo already pins, so nothing else moves.

Build and specs: dotnet build -c Release zero warnings, 436 specs green — same as the baseline on main.