Release v4.16.0

Added

• The opt-in semantic Stage engine (Stage__Runtime__Engine=semantic) can start on a Chronicle event log that already holds events. It rebuilds its semantic world only when that can be done exactly: every projection is mirrored exactly and has caught up with its own events without failed partitions, every logged event converts back exactly, and the history satisfies the model's constraints. Otherwise it refuses with a specific Unsupported(World) status. (part of #23)

Changed

• The semantic engine reports loading while it rebuilds, and refuses requests until it is ready. After any append by another client it stops serving requests rather than drift from the log. (part of #23)
• A rebuild is refused for event contracts with date-time or decimal properties, because Chronicle's storage changes those values (offsets, precision). It is also refused for null optional values, non-text destinations, a causedBy name that changed over time, and duplicate tags. The bundled sandbox container resets its kernel on restart, so rebuilding applies when the host runs against an external or persistent Chronicle. (part of #23)