Add GitHub Action for catalog service tests

- Runs on pull requests and main branch pushes
- Only triggers when catalog service files change
- Runs npm install and npm test for the catalog service
- Will show failing checks if unit tests fail

Author: loujaybee

.github/workflows/catalog-tests.yml

@@ -0,0 +1,38 @@
+name: Catalog Service Tests
+
+on:
+  pull_request:
+    branches: [ main ]
+    paths:
+      - 'backend/catalog/**'
+      - '.github/workflows/catalog-tests.yml'
+  push:
+    branches: [ main ]
+    paths:
+      - 'backend/catalog/**'
+      - '.github/workflows/catalog-tests.yml'
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    
+    defaults:
+      run:
+        working-directory: backend/catalog
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '20'
+        cache: 'npm'
+        cache-dependency-path: backend/catalog/package-lock.json
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Run tests
+      run: npm run test