v3.4.0

release: bump version to 3.4.0, update docs and benchmarks

- Version 3.3.0 → 3.4.0 in pyproject.toml, __init__.py, PUBLIC_API.md,
  CITATION.cff, .zenodo.json
- CHANGELOG.md: add [3.4.0] section with Phase 3 summarization FPR fix
- BENCHMARK_REPORT.md: add summarization FPR section (95% → 25.5%)
- COMPETITOR_COMPARISON.md: update version, summarization weakness notes
- README.md: update test badge (1991), citation version, limitations
- docs-site/changelog.md: add v3.4.0 entry
- demo/requirements.txt: bump to >=3.4.0
- Fix version assertions in test_consumer_api.py, test_v330_hardening.py
- Update latency_bench.py banner to v3.4.0

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