Release v16.13.4

Summary

• Fixed ExpandoObjectExtensions.Clone() and AsExpandoObject() treating any dictionary as a plain enumerable and "listifying" it into a List<KeyValuePair<,>>, which serialized as an array of { Key, Value } documents instead of an object. Clone() runs on every changeset computation, so a dictionary-shaped (additionalProperties) property could be corrupted the moment its containing state was cloned for the next event.
• Fixed the same class of bug independently in Storage.Sql's UnwrapForJson, which only recognized IDictionary<string, object?> and missed the Dictionary<object, object> shape a schema dictionary actually round-trips as.
• Since both fixes live in code shared by every storage engine (MongoDB, SQL Server, PostgreSQL, and the in-memory sink), all are covered by these changes.

Fixed

• Dictionaries with additionalProperties schemas no longer get corrupted into an array of { Key, Value } documents when their containing object's state is cloned for a subsequent event (#3568)
• SQL Server / PostgreSQL read models now correctly serialize schema-defined dictionary properties as JSON objects instead of arrays

Test plan

• Infrastructure.Specs — 2 new unit specs for Clone()/AsExpandoObject() covering dictionary values (confirmed failing before the fix, passing after)
• Storage.MongoDB.Specs — new integration spec against a real MongoDB container proving a dictionary survives a first write and a subsequent sibling-property update
• Storage.Sql.Specs — new SQLite-backed spec for the same scenario (confirmed failing before the fix, passing after)
• Storage.InMemory.Specs and Core.Specs — full regression run, no failures
• Debug and Release builds clean, zero warnings, for all touched/dependent projects