Clean outside-in DDD boundaries

[eviltester]

Summary

• move transport classes into explicit adapter packages
• resolve request context once and map errors through ApiMappingError
• move relationship body reference resolution into ThingCommandService
• add architecture/request/relationship rollback guardrail tests

Verification

• mvn spotless:check
• mvn -pl ercoremodel,thingifier,challenger -am pmd:check checkstyle:check
• mvn test
• mvn -pl thingifier,challenger -am verify
• mvn -pl challengerAuto -am test -Dchallenger.auto.target=local -Dchallenger.auto.local.repository=memory -Dchallenger.auto.local.playerMode=single
• mvn -pl challengerAuto -am test -Dchallenger.auto.target=local -Dchallenger.auto.local.repository=sqlite-memory -Dchallenger.auto.local.playerMode=single

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