Check in CI that data survives a Docker restart

The docker job now records an attempt, stops the stack without removing
volumes, starts it again, logs in with the same account and checks the
attempt is still there. This covers the last step of the V3 success
criteria, which nothing tested before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: CanYouTeachMeHowToCode

.github/workflows/ci.yml

@@ -151,6 +151,7 @@ jobs:
 
       - name: Wait for the backend to become healthy
         run: |
+          cat > wait-for-backend.sh <<'EOF'
           for i in $(seq 1 60); do
             if curl -sf http://localhost:8000/health > /dev/null; then
               echo "backend healthy after ${i} tries"
@@ -160,6 +161,8 @@ jobs:
           done
           echo "backend did not become healthy" >&2
           exit 1
+          EOF
+          bash wait-for-backend.sh
 
       - name: Smoke test through nginx
         run: |
@@ -177,6 +180,25 @@ jobs:
             http://localhost:8080/api/auth/register > /dev/null
           curl -sf -b cookies.txt http://localhost:8080/api/sekiro/analytics | jq -e '.total_bosses == '"${bosses}"
 
+          # An attempt for the persistence check below.
+          curl -sf -b cookies.txt -H 'Content-Type: application/json' \
+            -d '{"result": "failed", "phase_reached": 1, "failure_move_id": null, "failure_category": "not_sure", "notes": "persistence check"}' \
+            http://localhost:8080/api/bosses/genichiro-ashina/attempts > /dev/null
+
+      # Stopping the stack without -v must keep accounts and attempts in the
+      # postgres-data volume (V3 success criteria: restart, data persists).
+      - name: Restart the stack and check the data persisted
+        run: |
+          docker compose down
+          docker compose up -d
+          bash wait-for-backend.sh
+
+          curl -sf -c cookies-after.txt -H 'Content-Type: application/json' \
+            -d '{"username": "ci_smoke", "password": "ci-smoke-password"}' \
+            http://localhost:8080/api/auth/login > /dev/null
+          curl -sf -b cookies-after.txt http://localhost:8080/api/bosses/genichiro-ashina/attempts \
+            | jq -e 'length == 1 and .[0].notes == "persistence check"'
+
       - name: Show container logs
         if: failure()
         run: docker compose logs