Release v4.178.0

Added

• Applications rendered with classic reducers can migrate individual read models to self-reducing read models. A per-read-model override in .cratis/stage/rendering.json (version 2) selects the self-reducing form, and the read model then carries [Reducer("<previous reducer full name>")] on every render, so Chronicle keeps the existing observer instead of starting a new one. See Migrating a classic read model. (#464)
• ArtifactRenderPlan.RequiredRemovals lists files a publisher must delete together with the plan's writes (path, expected SHA-256 and read model), and ReducerMigrationEvidence.FromExistingFile builds migration evidence from the existing reducer file. Migration is refused with STAGE-REDUCER-001 to STAGE-REDUCER-004 when the override, evidence, removal capability or plan scope does not allow it. (#464)
• CratisRendering.CheckPublication returns UnsafeRemovals (STAGE-REDUCER-005) when a file to remove has changed since the evidence was taken, or when a migrated read model's previous reducer file would be left behind. (#464)