PNR analysis notebooks: refnx fitting and Fisher optimisation (HOGBEN)

Zenodo ready release of HOGBEN-optimising-PNR associated with the paper titled "Improving polarised neutron reflectometry experiments on soft-matter samples: optimisation of the solid substrate structure". Contents: fitting workflows Fisher/HOGBEN optimisation workflows figure-generation helpers used for the manuscript Notes: Release prepared for archival via Zenodo Intended as the citable version used in the paper