ci(portal-self-service): serve the self-service app in compose (refs #68)

Add the self-service nginx service (build the app image, depends_on bff healthy +
keycloak started, health-checked, host port 8140). Add it to WAIT_SVCS and the CI
log dump.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.gitea/workflows/ci.yaml

@@ -127,7 +127,7 @@ jobs:
       # Log dump must precede teardown (which removes the containers).
       - name: Dump container logs on failure
         if: failure()
-        run: docker compose -f infra/docker-compose.yml logs --no-color --tail=100 oz-init openzaak nrc-init nrc-web nrc-celery nrc-beat flowable-db flowable-rest flowable-init keycloak acl bff domain projection-db event-subscriber projection-api 2>&1 || true
+        run: docker compose -f infra/docker-compose.yml logs --no-color --tail=100 oz-init openzaak nrc-init nrc-web nrc-celery nrc-beat flowable-db flowable-rest flowable-init keycloak acl bff domain projection-db event-subscriber projection-api self-service 2>&1 || true
       - name: Tear down
         if: always()
         run: make down