Strengthen Core 4 compare conformance

[hyeokjun32]

Summary

• Extend Core 4 conformance to build the committed Studio compare bundle
• Validate Lab compare top-level/data/rendered aliases, rendered outputs, comparison mode, and Lab-owned policy decision surface
• Document the stronger compare bundle coverage in README

Tests

• poetry run inferedgelab core4-conformance-check
• poetry run inferedgelab portfolio-demo-check
• poetry run python3 -m pytest -q tests/test_core4_conformance.py
• poetry run python3 -m pytest -q tests/test_core4_conformance.py tests/test_ci_doc_guards.py
• poetry run python3 -m pytest -q
• git diff --check