chore: add pr workflow to catch build errors early

Author: wkillerud

.github/workflows/pull-request.yml

@@ -0,0 +1,22 @@
+name: Pull request
+
+on:
+  pull_request:
+    branches:
+      - source
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Build website
+        run: npm run build