Release v4.87.0

Added

• A public .NET API for scoped validation: ScopedDiagnostics.TryValidate in Cratis.Screenplay.Mcp takes a file or folder path (or the sources in memory), a module, feature or slice address and the completeness checks to run, and returns the scope's diagnostics, its direct dependents, the affected scopes, unresolved event consumers and the whole application's error and warning counts. An unknown or ambiguous scope and an unreadable path are reported as errors. The screenplay tool and the MCP diagnostics tool use the same implementation (#533)