Upstream non-Leios commits from the Leios integration branch to master

[Jimbo4350]

Companion to IntersectMBO/cardano-api#1291.

Before starting: confirm with Sebastian Nagel which Leios integration branch is the relevant one (leios-prototype and jl/leios-prototype-remake both exist).

The Leios integration branch carries changes that are not Leios-specific and should land on master rather than diverge on the prototype branch.

Task:

• Confirm the relevant branch with Sebastian.
• Audit its commits and identify everything that builds against released dependencies — noting that some picks may depend on the corresponding cardano-api changes reaching master first.
• Bring those changes onto master via normal PRs — cherry-pick where the commits apply cleanly, or manually integrate where they don't.
• Rebase the Leios branch so it carries only Leios-specific work.