ci: stop one red gate from disarming every gate below it

GitHub Actions skips all later steps in a job once one fails, so the
doc-truthing failure silently disarmed the soundness-ledger gate, the
capability-anchor gate and the formatting check. Those report `skipped`,
not `failure` -- worse than red, because `skipped` reads as absence of news
rather than as a gate that never ran.

`if: ${{ !cancelled() }}` makes the four gates independent: each reports its
own verdict regardless of the others, while a cancelled run still stops.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/ci.yml

@@ -100,6 +100,7 @@ jobs:
         # rationale + recovery instructions.
         run: ./tools/check-no-extension-ts.sh
       - name: Issue #176 — doc-truthing re-drift guard (DOC-01..09)
+        if: ${{ !cancelled() }}
         # Single toolchain-free gate enforcing both halves of the doc-truthing
         # MONITOR: the presence invariants (DOC-04/05 — banner pointers, matrix
         # primacy + anti-over-claim section, STATE.a2ml mirror keys) AND the
@@ -108,6 +109,7 @@ jobs:
         # See tools/check-doc-truthing.sh.
         run: ./tools/check-doc-truthing.sh
       - name: Soundness-ledger anti-staleness gate
+        if: ${{ !cancelled() }}
         # docs/SOUNDNESS.adoc is the single source of truth for soundness-hole
         # status. This gate fails if the ledger loses its primacy declaration or
         # freshness stamp, if any test fixture it names as an anchor goes
@@ -116,13 +118,15 @@ jobs:
         # See tools/check-soundness-ledger.sh.
         run: ./tools/check-soundness-ledger.sh
       - name: Capability-matrix test-anchor gate
+        if: ${{ !cancelled() }}
         # docs/CAPABILITY-MATRIX.adoc anchors each feature-readiness claim to an
         # executable test ("== Test anchors"). This gate fails if that section
         # disappears or if any test it names goes missing — so a "works" status
         # row cannot outlive the test that backs it.
         # See tools/check-capability-anchors.sh.
         run: ./tools/check-capability-anchors.sh
       - name: Check formatting
+        if: ${{ !cancelled() }}
         run: opam exec -- dune build @fmt
   lint:
     runs-on: ubuntu-latest