v2.3.0 — gate contradictions

A review-only pass over all 19 skills found eight defects, all of them contradictions between
files that read correctly in isolation. This release closes all eight.

Blockers

duck-plan's naming rule broke duck-scan's read-only guarantee. It said "a skill named
inside another skill's step is an instruction to invoke it, not a citation" — absolutely, which
turned duck-scan's mention of duck-cut into a dispatch two lines above where duck-scan says
"the skills do the acting". Nine citations across the corpus sat under the same rule. Now scoped
to imperative steps.

A converging third review round was undispatchable. duck-review refused every N≥3 dispatch
without a committed loop-diagnosis:, but duck-run only minted one when the loop was diverging.
Both now turn on the same predicate, and a converging loop is an exit like the other four.

duck-run's Verify stage inverted its own scratchpad rule — "never the scratchpad, which is
where the gate looks". The relative clause attached to the scratchpad.

Gaps

• duck-race's receipt was the only one homed in $SP, which dies before the stage that reads it.
• The receipt commit path was unstated corpus-wide. It goes on a records branch, never base — a
  receipt landed on base advances what duck-land re-verifies and voids the authorization the
  receipt exists to support.
• duck-review named the model-pin proof and declined to enforce it while duck-race mandated the
  same control, deferring to "the soul" — a reference resolving nowhere in the corpus. Now binding
  in both.
• duck-plan deferred a co-author count to duck-review's bar without stating it. Now two.
• REQUIRED_REFERENCES covered 1 of 8 load-bearing delegations, so five of the pipeline's own
  links could be deleted with the validator green. Each new row is mutation-tested.

Minor rather than patch: behaviour tightened rather than only repaired.

How it was reviewed

Two rounds against a roster-proven different model family. Round 1 rejected the change on a
defect in the fix itself — the rewritten breaker claimed to fire "earlier than" its round count,
which is impossible, since remediation-born blockers need three rounds to occur twice. Deleted
rather than repaired. Round 2 approved.

Reviewed by one family rather than two: the second outaged on credits and the owner waived the
two-family requirement for round 2 only.

Full changelog: v2.2.0...v2.3.0