[Docs]: Add Jupyter notebook examples

[harryswift01]

Documentation Update

Create reproducible Jupyter notebooks showing how to run and analyse SIST through the public Python API.

Why Is This Needed?

Notebooks are widely used for molecular-simulation analysis and provide an accessible way to demonstrate the complete workflow.

Suggested Changes

Create examples covering:

• Running a small calculation.
• Inspecting results, metadata, and warnings.
• Saving a structured result.
• Loading and analysing a saved result.
• Comparing multiple results.
• Exporting processed data.

The notebooks should use small, redistributable datasets and only public APIs.

Done When

• An introductory calculation notebook is available.
• A saved-result analysis notebook is available.
• A result-comparison example is available.
• The notebooks run in a clean documented environment.
• Saved-result analysis does not rerun SIST.
• Notebook execution is tested automatically.