[codex] Release UsEquityStrategies v0.7.27

[Pigbibi]

Summary

• bump UsEquityStrategies to v0.7.27
• update QuantPlatformKit dependency to v0.7.18 so downstream platforms can consume the strategy plugin runtime loader without pip conflicts

Validation

• git diff --check
• .venv/bin/ruff check .
• PYTHONPATH=src:../QuantPlatformKit/src .venv/bin/python -m unittest discover -s tests -v