chore(trust): flip the signing checks to the new release root

v1.7.122-alpha was the last release signed with the old root — it is the
release that installed the new pin on every node. From v1.7.123 the new
root signs, and a node running .122+ rejects an old-key signature. The
ARCHY_RELEASE_ROOT_PUBKEY override is no longer needed either: the signer
built from this tree pins the same key we now sign with.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/publish-release-assets.sh

@@ -29,11 +29,9 @@ fail() { echo "Error: $*" >&2; exit 1; }
 # with the pinned release-root anchor refuse to auto-apply unsigned manifests,
 # and enforcement will tighten to hard-reject — an unsigned publish would
 # strand them. Grep proves presence; ceremony verify proves the crypto.
-# ⚠ ROTATION IN FLIGHT (v1.7.122-alpha) — OLD root on purpose; see the same
-# block in create-release.sh. Nodes still run the previous binary and pin the
-# old key, so the manifest this release publishes must carry an old-key
-# signature. Flip both to z6Mkfu5LT…DLWT for v1.7.123+.
-EXPECTED_DID="did:key:z6MkkidEnEpo6qHMCNSZoNKWtvQvxq3whnaME9wGgEFhq7ur"
+# Release root ROTATED 2026-08-05; see create-release.sh. New root from
+# v1.7.123 onward.
+EXPECTED_DID="did:key:z6Mkfu5LT8d4DjETtrkATvHh9Dvcbnr7zBCUwfau8Sw7DLWT"
 grep -q '"signature":' "$PROJECT_ROOT/releases/manifest.json" \
     && grep -q "\"signed_by\": \"$EXPECTED_DID\"" "$PROJECT_ROOT/releases/manifest.json" \
     || fail "releases/manifest.json is not signed by the release root — run: bash scripts/sign-manifest.sh"