Release v19.112.4

Fixed

• A root-level projection join now routes by its declared key expression (UsingKey(e => e.Property) in the fluent builder, or the key of a variant's non-entering event) instead of always by the event source id. A join event appended to another event source now updates the read model whose On property matches the key value. When the key property is missing or null, the join falls back to the event source id. A root join that declares a context, constant or composite key logs a warning and uses the event source id. Joins whose key equals the event source id behave as before. Existing read models built with a differing key keep their earlier state until their projection is replayed (#4165)
• ReadModelScenario and EventScenario in Cratis.Chronicle.Testing route root joins the same way the kernel does, so in-process specs match production behavior.