ci: add frontend build and test workflow

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

.github/workflows/frontend-ci.yml

@@ -0,0 +1,34 @@
+name: Frontend CI
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 15
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+
+      - name: Setup Node
+        uses: actions/setup-node@v6
+        with:
+          node-version: 20
+          cache: npm
+          cache-dependency-path: package-lock.json
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build frontend
+        run: npm run build
+
+      - name: Run unit tests
+        run: npm run test