refactor: Unified Sync/Async Tool Interface

[rayrishu19-wq]

This PR addresses Issue #8 by merging separate sync and async tools into a single interface using a background parameter.

Changes:

• Merged fit_predict_tool and fit_predict_async_tool in fit_predict.py.
• • Merged load_data_source_tool and load_data_source_async_tool in data_tools.py.
• • Updated server.py to use unified tool registration.
• • Updated test suite to align with new interface.

Verification:

• All 132 tests passed locally.