Make CI the default environment

[kennethbruskiewicz]

Summary

• define CI once as the global runtime default
• prefer the selected SmartAPI provider environment
• fall back through non-test provider URLs before using test
• document CI defaults with test as the explicit override example
• add regression coverage for defaults and provider URL precedence

Testing

• uv run pytest -q tests/test_config.py tests/test_tools.py
• 11 tests passed

Closes #59