Harden physical hardware assistant validation

[tsotchke]

Summary

• add ASTRESS.LOG to the physical hardware capture path and copy-back checklist
• require five assistant packs plus the 50-reply stress probe in hardware capture verification
• refresh QEMU hardware-capture evidence and preview manifest with the hardware stress report

Verification

• QEMU hardware capture rehearsal: PASS with ASTRESS.LOG, 50 stress replies
• python3 scripts/verify_hardware_capture.py --capture-dir qemu/evidence/hardware_capture_486_qemu
• python3 scripts/stress_assistant_behavior.py --log qemu/evidence/hardware_capture_486_qemu/ASTRESS.LOG --report qemu/evidence/hardware_capture_486_qemu_stress_report.md
• .venv-torch311/bin/python -m unittest discover tests
• python3 scripts/verify_assistant_packs.py
• .venv-torch311/bin/python scripts/verify_preview_artifacts.py
• LC_ALL=C LANG=C shasum -a 256 -c release sidecars