The actual drift was NOT OccurredAtUtc's converter (a same-CLR-type
DateTime->DateTime ValueConverter emits no snapshot annotation and never
triggers PendingModelChangesWarning). The real pending change was a HasData
seed row: SecurityConfiguration adds LdapGroupMapping Id=5 (SCADA-Viewers ->
Viewer) but the model snapshot omitted it, so MsSqlMigrationFixture's
MigrateAsync threw PendingModelChangesWarning and failed every fixture-backed
AuditLog MSSQL test (~57).
Generated via `dotnet ef migrations add`; Up/Down are seed-data DML only
(InsertData/DeleteData of the single reference row) -- no schema DDL. The
snapshot now carries the Id=5 seed and has-pending-model-changes is clean.
Joseph Doherty