ci: Set up node environment & cache

.github/workflows/dev.yml

@@ -7,8 +7,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Install dependencies
+      - name: Set up node & dependencies
-        run: npm i
+        uses: actions/setup-node@v4
+        with:
+          node-version: 18
+          cache: "npm"
+      - run: npm ci    
       - name: Run the TypeScript build
         run: npx tsc
       - name: Create server-package.json