ci: add post-deploy verification — catch broken Pages config on every deploy

Foundational fix for the incident where making the repo private
wiped GitHub Pages config (CNAME, custom domain) and the site
stayed down because GitHub's CDN cached the 404. Every deploy now
verifies that sovren.software returns HTTP 200 after CDN propagation.
If it doesn't, the workflow fails loudly instead of silently serving a 404.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ccross2

.github/workflows/deploy.yml

@@ -40,3 +40,19 @@ jobs:
     steps:
       - uses: actions/deploy-pages@v4
         id: deployment
+
+  verify:
+    needs: deploy
+    runs-on: ubuntu-latest
+    steps:
+      - name: Wait for CDN propagation
+        run: sleep 15
+
+      - name: Verify site is live
+        run: |
+          STATUS=$(curl -sI -o /dev/null -w "%{http_code}" https://sovren.software/)
+          echo "sovren.software returned HTTP $STATUS"
+          if [ "$STATUS" -ne 200 ]; then
+            echo "::error::Site returned $STATUS — expected 200. Check Pages config and custom domain."
+            exit 1
+          fi