feat: refactor and update proof types

[atanmarko]

Description

Update proof types to match latest proto changes.

Fixes #86

PR Checklist:

• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added or updated tests that comprehensively prove my change is effective or that my feature works

[iljakuklic]

Looks good to me code-wise. However, I am missing some context regarding the motivation for these changes.

[atanmarko]

Note: put to draft to rebase on top of #84