Tighten the What's New > Changelog > Update flow and roll it out to more than Develop


We have this in Develop only. I'd like us to polish it and consider rolling it out for other versions (Nightly, Web, & Desktop)

We need to discuss this more (and especially where it lands on our priorities list but...) I'd like to:

```[tasklist]
### Tasks
- [ ] Make the button on the left a secondary button and have it open the changelog
- [ ] Make the button on the right the primary button and have it take users straight to upgrade
- [ ] Update the layout of the changelog dialog so that it's easier to read
- [ ] Implement a changelog process internally where these are written as release notes, not links to GH tickets
- [ ] Discuss rolling it out on other versions of our product suite
- [ ] Discuss how ESS users might be able to change or tailor the content
```

Start by reviewing the existing What's New > Changelog > Update flow in Develop and the attached screenshot. Define the desired button hierarchy, changelog dialog layout, rollout targets, release-note process, and ESS customization approach; done requires agreement on these broader product decisions before implementation.

Written by the indexing model from the issue text.