Fix runtime combo registry dependencies

[Pigbibi]

Summary

• remove direct runtime import of the migrated QuantUsComboStrategies package
• keep US combo strategies available through UsEquityStrategies catalog/runtime adapters
• sync QPK/US/HK dependency constraints and keep runtime guard failure artifact handling enabled

Tests

• python3 -m py_compile strategy_registry.py strategy_loader.py scripts/build_cloud_run_env_sync_plan.py
• python3 -m py_compile scripts/cloud_run_runtime_guard.py
• git diff --check