R-528 red-proof red-go-kept: the copy of oom_check removed from internal/osupdate/unsent.go
mutation: `rep.OOMCheck = rawOrNil(wr.OOMCheck)` -> `_ = rawOrNil`
$ go test ./internal/osupdate/ -run ^TestR868_KeptCopyCarriesTheOOMCheck$ -count=1
rc=1
2026/10/06 19:13:38 INFO osupdate: sending a kept report late (the agent was stopped mid-pass or the hub was away, R-868) run=20261007T020000Z layer=docker vmid=9201 ring=0 trigger=night path=/tmp/TestR868_KeptCopyCarriesTheOOMCheck2908158053/001/report-20261007T020000Z-docker-apply.json
2026/10/06 19:13:38 INFO osupdate: DONE run=20261007T020000Z layer=docker vmid=9201 ring=0 trigger=night outcome=applied healthy=true reason="sent late — kept on the box until the hub could take it (R-868, R-875)" upgraded=1 pending=0 not_covered=0 restart_needed=0 reboot_needed=false wrapper_seconds=0
--- FAIL: TestR868_KeptCopyCarriesTheOOMCheck (0.00s)
    unsent_test.go:171: oom_check lost or changed: ""
FAIL
FAIL	gitea.dooplex.hu/admin/felhom-agent/internal/osupdate	0.008s
FAIL

=== control: restored source ===
$ go test ./internal/osupdate/ -run ^TestR868_KeptCopyCarriesTheOOMCheck$ -count=1
rc=0
ok  	gitea.dooplex.hu/admin/felhom-agent/internal/osupdate	0.009s
VERDICT: RED as expected, GREEN restored