fix(shell): remove runtime early-exit pipe hazards (#1105)

Co-authored-by: f10-coder <[email protected]>

tools/e2e-gateway-verify-supported.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Exit 0 only when the capability probe itself succeeds and advertises verify.
+# A failed help command and a successful response without verify are both
+# unsupported, matching the historical e2e-install-test.sh conditional.
+set -uo pipefail
+
+gateway_help_rc=0
+gateway_help="$(mosaic gateway --help 2>&1)" || gateway_help_rc=$?
+[[ "$gateway_help_rc" -eq 0 ]] || exit 1
+grep -q 'verify' <<<"$gateway_help"