Add missing release notes for PRs in this engagement

[alexdewar]

Description

Seeing as I'm now off (yay!) I thought I'd try to use up some of my remaining Copilot tokens 😉.

The release notes is a bit out of date and there are some things that we probably want to note in there. I got Copilot to go through the merged PRs and add missing entries where relevant. I've gone through and edited it down, but on the whole I think it's done a good job. I've checked that all the links are correct.

I left out things, like investment constraints, that are still in progress.

While we don't want to make this document overly long, but at the same time, it's important to flag all the nice things we've achieved here 😄.

Type of change

• Bug fix (non-breaking change to fix an issue)
• New feature (non-breaking change to add functionality)
• Refactoring (non-breaking, non-functional change to improve maintainability)
• Optimization (non-breaking change to speed up the code)
• Breaking change (whatever its nature)
• Documentation (improve or add documentation)

Key checklist

• All tests pass: $ cargo test
• The documentation builds and looks OK: $ cargo doc
• Update release notes for the latest release if this PR adds a new feature or fixes a bug
  present in the previous release

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.80%. Comparing base (2d4fd29) to head (0c378e3).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1467   +/-   ##
=======================================
  Coverage   89.80%   89.80%           
=======================================
  Files          60       60           
  Lines        8443     8443           
  Branches     8443     8443           
=======================================
  Hits         7582     7582           
  Misses        544      544           
  Partials      317      317           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.