feat: preserve manifest source model identity

[hyeokjun32]

Summary

• Preserved Forge manifest source model identity when generating Runtime compare keys.
• Prevented TensorRT model.engine paths from degrading compare_model_name to model.
• Added/updated tests for manifest-based compare key generation and fallback behavior.

Validation

• cmake --build build -j — success
• ctest --test-dir build --output-on-failure — success; no CTest tests registered in this build tree
• bash scripts/smoke_forge_handoff.sh — success
• scripts/smoke_default.sh — success
• python3 tests/test_forge_handoff.py && python3 tests/test_lab_result_schema.py && python3 tests/test_lab_worker_adapter_contract.py && python3 tests/test_manifest_compare_identity.py — success
• Jetson TensorRT manifest identity smoke was not executed in this local macOS environment

Impact

• Improves Forge → Runtime → Lab compare readiness.
• Keeps compare_key aligned with the original ONNX model identity.
• Reduces provenance ambiguity for TensorRT engine artifacts.

Notes

• This does not add a production worker daemon or production SaaS infrastructure.
• It is a provenance/compare-readiness polish for the existing Runtime result export path.