Enforce mutually exclusive auth connections

Changed

• api_key and limited_access_key are now mutually exclusive in NucleusClient. Passing both (or setting NUCLEUS_API_KEY while also passing limited_access_key) raises a ValueError.

Fixed

• Docstring improvements across NucleusClient: fixed copy-paste errors (get_job, get_slice, delete_slice), removed phantom stats_only parameter from list_jobs, corrected make_request parameter name, and restructured create_launch_model/create_launch_model_from_dir docs for proper rendering.
• Suppressed Sphinx warnings from inherited pydantic BaseModel methods by removing inherited-members from autoapi options.