Refactor polars handling and add external plotting tools

[tomjholland]

This pull request includes several changes across different files to improve the documentation and testing processes, as well as to update the examples with new plotting methods.

Features:

• Wrapper for pandas .plot() method to allow quick plotting from all results object
• Wrapper for hvplot() method for quick dynamic plotting
• Wrapper for seaborn
• Read data without a readme file

Enhancements:

• Refactor polars handling so that requested columns are cached to minimise calls to polars .collect() method

Refactor:

• Removed units from column definitions

Documentation and Testing Updates:

• CONTRIBUTING.md: Added a note to follow the angular commit style and updated the test command to use uv run pytest instead of pytest. [1] [2]
• docs/source/developer_guide/developer_installation.rst: Simplified the virtual environment setup command to use uv sync --all-extras --all-groups.

Example Updates:

• docs/source/examples/LEAN-differentiation.ipynb: Replaced pyprobe.Plot with matplotlib.pyplot for plotting and updated the plotting commands accordingly. Closes Address performance issues running Plot.show_image() #145 [1] [2] [3] [4] [5]
• docs/source/examples/analysing-GITT-data.ipynb: Updated the plotting commands to use matplotlib.pyplot instead of pyprobe.Plot. [1] [2] [3] [4] [5] [6]
• docs/source/examples/differentiating-voltage-data.ipynb: Changed the plotting method from pyprobe.Plot to matplotlib.pyplot and updated the plotting commands. [1] [2] [3] [4] [5] [6] [7]
• docs/source/examples/filtering-data.ipynb: Replaced pyprobe.Plot with matplotlib.pyplot for plotting and updated the plotting commands. [1] [2]

Workflow Configuration:

• .github/workflows/ci.yml: Removed the installation step for nbmake and updated the test command to use uv run pytest --nbmake.