After/: plain Client/Order (no DbBase), ClientDto/OrderDto records
carrying the relations both ways, hand-written Mappers with a
reference-identity cache for the back-reference cycle, DbContext with
explicit Save(domain) via shadow entities (flipped dependency), and a
WebApp that consumes only DTOs. AfterTests cover the 7 required
behaviours; full solution builds with 0 warnings, 26/26 tests pass.
