docs: improve portfolio pdf rendering

[hyeokjun32]

Summary

• Shorten long inline paths and nested field names in the current portfolio PDF source.
• Preserve the same Jetson evidence numbers, Runtime Intelligence ownership boundary, and production non-goal wording.
• Keep the generated PDF under ignored artifacts/, not committed.

Validation

• git diff --check
• bash scripts/export_portfolio_pdf.sh
• gs -dNOPAUSE -dBATCH -sDEVICE=png16m -r120 -sOutputFile=/private/tmp/inferedge_portfolio_pdf_pages/page-%03d.png artifacts/portfolio/inferedge_portfolio_submission.pdf
• Visual PNG review: 6 pages rendered; page 4 right-margin clipping fixed
• poetry run inferedgelab portfolio-demo-check
• PYTHONDONTWRITEBYTECODE=1 poetry run python3 -m pytest tests/test_runtime_intelligence_evidence_chain_smoke.py tests/test_runtime_intelligence_bundle_manifest.py tests/test_runtime_intelligence_artifact_gate.py tests/test_runtime_intelligence_ci_template.py -q -p no:cacheprovider