Add build CI

.github/workflows/build.yml

@@ -0,0 +1,33 @@
+name: CI
+on: [push]
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set Node.js 16.x
+        uses: actions/setup-node@v3
+        with:
+          node-version: 16.x
+
+      - name: Run install
+        uses: borales/actions-yarn@v4
+        with:
+          cmd: install # will run `yarn install` command
+      - name: Build production bundle
+        uses: borales/actions-yarn@v4
+        with:
+          cmd: build:prod # will run `yarn build:prod` command
+      - name: Test the app
+        uses: borales/actions-yarn@v4
+        with:
+          cmd: test # will run `yarn test` command
+
+      - name: Run test in sub-folder
+        uses: borales/actions-yarn@v4
+        with:
+          cmd: test
+          dir: 'build' # will run `yarn test` in `frontend` sub folder