Pages: keep NODE_ENV "production", don't run yarn

.gitlab-ci.yml

@@ -86,8 +86,12 @@ docs-deploy:
 
 pages:
   stage: deploy
+  before_script: ""
   script:
+    # artifacts are kept between jobs
     - mv static public
+  variables:
+    NODE_ENV: production
   artifacts:
     paths:
     - public