feat: add latency regression problem case

[hyeokjun32]

Summary

• Added a latency regression problem case for Local Studio demo evidence.
• Added same-backend TensorRT Jetson baseline/regressed fixtures and a review_required deployment signal.
• Updated Studio problem-case rendering and portfolio validation docs.

Validation

• poetry run python3 -m pytest tests/test_studio_routes.py tests/test_validation_demo_report.py -q
• poetry run python3 -m pytest -q

Impact

• Shows InferEdge catches latency regressions, not only latency improvements.
• Keeps the case focused on runtime performance evidence without mixing accuracy issues.

Notes

• No DB, queue, auth, upload, or production SaaS behavior was added.