fix(helpers): await async system results during evaluation

[Yash1hi]

Summary

async_run_and_evaluate passed awaitable system results directly to record creation, producing coroutine outputs or errors. It now awaits those results while continuing to support synchronous systems and concurrent trials. The synchronous helper raises a clear error directing callers to the async helper when a system returns an awaitable.

Changes

• Await system results before creating records.
• Update async system typing and helper docstrings.
• Reject awaitable results in the sync helper and close rejected native coroutines.
• Add mocked-client regression coverage without network access.

Testing

• .venv/bin/python -m pytest -q tests/lib/test_helpers.py — 24 passed.
• .venv/bin/ruff check src/scorecard_ai/lib/_helpers.py tests/lib/test_helpers.py — passed.
• .venv/bin/ruff format --check src/scorecard_ai/lib/_helpers.py tests/lib/test_helpers.py — passed.
• .venv/bin/pyright src/scorecard_ai/lib/_helpers.py tests/lib/test_helpers.py — 0 errors.