fix: stabilize local studio web workflow

[hyeokjun32]

Summary

• Stabilized the Local Studio browser workflow.
• Improved Run, Import, Compare, Decision, Jetson helper, and Pipeline state behavior.
• Added route/API contract tests for the local-first Studio workflow.

Validation

• poetry run python3 -m pytest tests/test_studio_routes.py -q
• poetry run python3 -m pytest -q
• Manual browser QA at /studio

Impact

• Makes Local Studio reliable as a portfolio/interview demo.
• Ensures the browser UI reflects actual imported/runtime evidence.
• Keeps the project local-first without adding production SaaS infrastructure.

Notes

• DB/queue/auth/billing remain future work.
• Jetson execution still runs on the local Jetson device or via generated command.