feat: add crucible image and sow-tools binary channel promote

tests/promote-crucible-contract.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+set -euo pipefail
+fail() { echo "FAIL: $*" >&2; exit 1; }
+promote="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)/scripts/promote-crucible.sh"
+[[ -f "$promote" ]]              || fail "promote-crucible.sh missing"
+grep -q 'STREAM_NAME=crucible'   "$promote" || fail "STREAM_NAME not crucible"
+grep -q 'STREAM_TIER=service'    "$promote" || fail "STREAM_TIER not service"
+grep -q 'skopeo inspect'         "$promote" || fail "require_release must use skopeo"
+grep -q 'deployment/crucible'    "$promote" || fail "wrong image path in skopeo"
+echo "promote-crucible-contract: OK"