Preserved development-test failure

The first run of tools/test-use-lab.cjs recovered all 64 delivered messages and passed
the altered-packet, wrong-head, wrong-tier and missing-working-snapshot checks. Its
last synthetic check then failed with:
  AssertionError [ERR_ASSERTION]: Missing expected exception.
  at tools/test-use-lab.cjs:23:53

The inherited test duplicated the checked snapshot, but the newly selected test packet
used working concepts only. The codec checks duplicate ambiguity when resolving a
reference; an unused duplicated snapshot did not exercise that condition.

Correction: select and duplicate the tier of an actual concept token in the test packet.
The expected rejection remains required. No codec, validator, source, definition,
message or normative state was changed. This was a test-fixture error, not a failed
recovery or a weakened artifact check. The successful rerun is in use-lab-tests.json.
