Link optional AIGuard source artifact

[hyeokjun32]

Summary

• add read-only source artifact traceability to the optional-present AIGuard alignment fixture
• validate the source artifact marker in the Runtime Intelligence CI artifact gate
• document that the source path points to the AIGuard full-evidence example without making it a required runtime contract

Design/docs consulted

• AGENTS.md
• examples/AGENTS.md
• tests/AGENTS.md
• docs/AGENTS.md
• Obsidian Runtime_Intelligence_Extension_Roadmap.md

Tests

• poetry run python3 -m pytest tests/test_runtime_intelligence_smoke_script.py tests/test_runtime_intelligence_ci_template.py -q -p no:cacheprovider
• poetry run python3 -m pytest tests/test_runtime_intelligence_bundle_manifest.py tests/test_runtime_intelligence_artifact_gate.py -q -p no:cacheprovider
• poetry run inferedgelab portfolio-demo-check
• poetry run python3 -m pytest -q -p no:cacheprovider