cicd: build and publish to GitLab Pages

.gitlab-ci.yml

+image: docker.io/node:lts-alpine
+
+pages:
+  stage: deploy
+  script:
+    - yarn && yarn build
+  artifacts:
+    paths:
+      - build
+  publish: build
+  rules:
+    - if: $CI_COMMIT_BRANCH == "deploy"