Enhance Jenkinsfile for E2E testing with PostgreSQL and Alembic migrations

- Added steps to ensure PostgreSQL service is ready before running Alembic migrations, improving the reliability of the E2E testing process.
- Implemented error handling for PostgreSQL readiness and Alembic upgrade commands to provide better feedback during CI runs.

Jenkinsfile

@@ -239,6 +239,37 @@ pipeline {
             echo "--- logs: celery_beat ---"
             docker logs --tail 200 celery_beat 2>&1 || true
           }
+          # Postgresql (app) + Alembic antes del resto: evita 10+ min "Waiting" mientras el lifespan
+          # migra y frontend/celery esperan service_healthy. El start de backend hará "upgrade" idempotente.
+          echo "== E2E: Postgres (app) + migraciones Antes del resto =="
+          if ! e2e_compose build backend; then
+            e2e_compose_fail_logs
+            exit 1
+          fi
+          if ! e2e_compose up -d postgres-a76; then
+            e2e_compose_fail_logs
+            exit 1
+          fi
+          _pg=0
+          while [ "$_pg" -lt 90 ]; do
+            if e2e_compose exec -T postgres-a76 pg_isready -U postgres -d anexo76_core 2>/dev/null; then
+              echo "E2E: Postgres (anexo76_core) acepta conexiones"
+              break
+            fi
+            _pg=$((_pg + 1))
+            sleep 2
+          done
+          if ! e2e_compose exec -T postgres-a76 pg_isready -U postgres -d anexo76_core 2>/dev/null; then
+            echo "ERROR: timeout esperando a postgres-a76"
+            e2e_compose_fail_logs
+            exit 1
+          fi
+          if ! e2e_compose run --rm --no-deps --entrypoint "" backend sh -c "set -eux; cd /app; alembic upgrade head"; then
+            echo "ERROR: falló alembic upgrade head (job previo al stack completo)"
+            e2e_compose_fail_logs
+            exit 1
+          fi
+          echo "== E2E: stack completo =="
           if ! e2e_compose up -d --build; then
             e2e_compose_fail_logs
             exit 1