Add release smoke path for pre-store verification (WP-0002)

Introduce npm run smoke with automated build, test, lint, dist, and
metadata-only compliance checks. Document manual Chrome steps in
RELEASE_SMOKE.md and fix unused imports blocking lint.

dev-helper.sh

@@ -36,6 +36,7 @@ usage() {
     echo "  open-chrome    - Open Chrome extension management"
     echo "  open-sw        - Open Chrome service worker internals"
     echo "  verify         - Verify dist build is valid"
+    echo "  smoke          - Full release smoke (build, test, lint, dist, metadata-only)"
     echo "  help           - Show this help"
     echo ""
     echo "Quick Test-Fix Loop:"
@@ -184,6 +185,9 @@ case "${1:-}" in
     verify)
         verify
         ;;
+    smoke)
+        bash "$(dirname "$0")/scripts/release-smoke.sh"
+        ;;
     help|--help|-h)
         usage
         ;;