add missing npm install, cached

Author: mlwilkerson

.github/workflows/browser-tests.yml

@@ -91,6 +91,17 @@ jobs:
           sudo npx playwright install-deps
           npx playwright install
 
+      - name: Cache node_modules
+        id: node-modules-cache
+        uses: actions/cache@v4
+        with:
+          path: admin/node_modules
+          key: ${{ runner.os }}-node-modules-${{ hashFiles('admin/package-lock.json') }}
+
+      - name: Install node dependencies
+        if: steps.node-modules-cache.outputs.cache-hit != 'true'
+        run: cd admin && npm install
+
       - name: Run Non-Kit Tests on Chrome
         run: cd admin && npm run test:browser-mocked-legacy-cdn-chrome