Nouveau update bundle

[rnewson]

Overview

A bundle of nouveau improvements, bundled for CI expediency but presented as a series of focused commits for review and posterity.

Testing recommendations

covered by existing tests, though many commits are aesthetic in nature (the ones converting classes to records)

Related Issues or Pull Requests

N/A

Checklist

• This is my own work, I did not use AI, LLM's or similar technology
• Code is written and works correctly
• Changes are covered by tests
• Any new configurable parameters are documented in rel/overlay/etc/default.ini
• Documentation changes were made in the src/docs folder
• Documentation changes were backported (separated PR) to affected branches