ci: add redirect tests to PR preview workflow

Updates the preview workflow to include a new job for testing redirects against the deployed preview URL.

Changes:
- Adds a `test_redirects` job that runs `npx mocha test-redirects.js` using the `preview_url` from the `build_drafts_on` job.
- Configures the redirect tests to run on Node.js 24.x in the `./test/redirects` directory.

Author: nathenharvey

.github/workflows/preview.yml

@@ -7,7 +7,7 @@ on:
     paths-ignore:
       - 'docs/**'
       - 'adrs/**'
-      - '.gemini/**'      
+      - '.gemini/**'
       - '**/README.md'
   workflow_dispatch:
 
@@ -135,4 +135,23 @@ jobs:
         run: |
           set -u
           npx playwright test --max-failures=1 --shard=${{ matrix.shard }}/${{ strategy.job-total }}
-  
+
+  test_redirects:
+    runs-on: ubuntu-latest
+    needs: build_drafts_on
+    defaults:
+      run:
+        working-directory: ./test/redirects
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Set up node
+        uses: actions/setup-node@v6
+        with:
+          node-version: '24.x'
+      - name: Install dependencies
+        run: npm ci --registry=https://registry.npmjs.org/
+      - name: Run redirect tests
+        env:
+          BASE_URL: ${{ needs.build_drafts_on.outputs.preview_url }}
+        run: npx mocha test-redirects.js

test/redirects/README.md

@@ -15,3 +15,6 @@ Optionally set a `BASE_URL` environment varilable to test redirects against a di
 
 `BASE_URL=https://staging.dora.dev npx mocha test-redirects.js`
 `docker run -it --env BASE_URL=https://staging.dora.dev test-redirects`
+
+These tests are run as part of the preview workflow on GitHub via the `test_redirects` job specified in the `preview.yml` file.
+