docs: clarify test dependency install in CLAUDE.md

The `pytest-asyncio` package is required for the async tests in
tests/test_sdk.py but is listed only under optional-dependencies.
Without it, `pytest tests/` silently fails 4 tests without any
error message — the tests just aren't collected.

Add a note to the Build and test section so developers know to
run `pip install -e ".[test]"` when running tests.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CLAUDE.md

@@ -26,7 +26,7 @@ Both packages are published together as `molecule-ai-sdk` on PyPI (`setuptools`,
 # Install in dev mode
 pip install -e .
 
-# Run the full suite
+# Run the full suite (requires test extras: pip install -e ".[test]")
 pytest
 
 # Run only molecule_agent tests (remote-agent client)