Add nix service definition for codex #4153

Job	Run time
matrix	18s
coverage	15m 16s
build / linux-unittest-amd64-pinned	14m 48s
build / linux-contract-amd64-pinned	8m 53s
build / linux-integration-amd64-pinned	14m 55s
build / linux-tools-amd64-pinned	9m 51s
build / macos-unittest-amd64-pinned	15m 7s
build / macos-contract-amd64-pinned	11m 33s
build / macos-integration-amd64-pinned	14m 54s
build / macos-tools-amd64-pinned	15m 1s
build / windows-unittest-amd64-pinned	14m 49s
build / windows-contract-amd64-pinned	15m 1s
build / windows-integration-amd64-pinned	14m 51s
build / windows-tools-amd64-pinned	14m 50s
build / status	1s
	3h 0m 8s

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