Release v3.15.0

Added

• A played event model that declares no screens now gets the screens it implies — one per slice, showing what the slice's read model holds and what its command does — so playing a model authored on Studio's canvas renders a working application instead of an empty page.
• The played frontend reads a read model through the query the Stage registered for it and submits a command from a form built off its schema, showing the validation results or errors the application returned.

Fixed

• A play session listed two event stores in the Chronicle Workbench. The event store name is now resolved once per container instead of once per process, so the handoff restart no longer registers a second store.
• A read model built by an automap projection stayed empty. Its shape is now taken from the events the projection maps from, and the identity property its documents are keyed by is declared when the model does not name one — without it every projection partition failed and the read model stayed empty for the whole session.
• Queries on a played model returned no data. They are now answered from the documents the session's own in-memory Chronicle built.