fix: correct client registry exports

[sparkyluvscode]

Summary

• Fixes the HuggingFace client import path in minions/clients/__init__.py.
• Removes BasetenClient from __all__ because no corresponding client implementation is present.
• Keeps the exported client registry aligned with available client modules.

Validation

• Verified the registry mismatch statically by checking minions/clients/.
• Attempted targeted import smoke test, but local import was blocked by missing optional dependencies (together after installing ollama; full pip install -e . not run due to heavy deps such as torch).
• The patch only updates the registry to match existing source files.

Notes

• This is intentionally scoped as a small registry consistency fix.