fix: harden backend stability and test production utilities

.gitea/workflows/backend-tests.yml

@@ -0,0 +1,29 @@
+name: Backend tests
+
+on:
+  push:
+    branches: [master, main]
+  pull_request:
+    branches: [master, main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: backend
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version-file: .nvmrc
+          cache: npm
+          cache-dependency-path: backend/package-lock.json
+      - name: Install dependencies
+        run: npm ci
+      - name: Audit production dependencies
+        run: npm audit --omit=dev
+      - name: Run backend tests
+        run: npm test