Clarify Lab README role boundaries

[hyeokjun32]

Summary:

• Add compact English/Korean README role-boundary tables for Lab.
• Keep Lab scoped to validation/report/API/job workflow and final deployment_decision ownership.
• Add README marker coverage so Forge/Runtime contracts, EdgeEnv comparability, AIGuard/Orchestrator ownership, and production SaaS boundaries do not drift.

Tests:

• poetry run python3 -m pytest -q tests/test_ci_doc_guards.py -p no:cacheprovider
• poetry run inferedgelab portfolio-demo-check
• poetry run python3 -m pytest -q -p no:cacheprovider
• git diff --check