ci: add build workflow

.github/workflows/build.yml

@@ -0,0 +1,23 @@
+name: Build
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  build-sass:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: "lts/*"
+          cache: "npm"
+
+      - name: Build
+        run: |
+          npm ci
+          npm run build