Fix pipeline-smoke-test artifact check to align with Titanic DB output

[Copilot]

The pipeline-smoke-test job failed because the workflow still referenced the old database artifact path. The pipeline now emits data/titanic.db, but CI was asserting data/demo.db.

• Root cause

  • CI smoke test contained a stale file assertion (data/demo.db) after the pipeline/database rename.

• Workflow alignment

  • Updated .github/workflows/ci.yml to use Titanic artifact names consistently in cleanup and output verification steps.
  • Replaced legacy demo.db references with titanic.db in the smoke-test path checks.

• Behavioral impact

  • CI now validates the actual outputs produced by pipelines/01_ingest_to_sqlite.py (data/titanic.db and reports/titanic_summary.csv) instead of a non-existent legacy artifact.

- name: Verify generated outputs
  run: |
    test -f data/titanic.db
    test -f reports/titanic_summary.csv

[Bmowville]

Closing this stale draft because the Titanic database workflow alignment was superseded by later merged CI/reporting work, and this PR no longer has a file diff against main.