[ivantopo]

This is very WIP. Don't bother too much looking at this.

I have been using Mill for other projects in the last year and IMHO the developer experience is considerably better once you get used to how the tasks are organized. More importantly, every time I needed to do something special with other Mill builds it was simpler to reason about the dependencies, how things are done in Mill, and how to make the adjustments I needed. I have 13+ years of using SBT and <1 year with Mill made me want to change and not look back. SBT served us well, but I don't want to use it anymore.

I don't have the energy and patience to make this a gradual migration with parallel SBT/Mill builds and we are going full big bang on this change.

Interesting changes and findings (will continue to update as I finish the process):

• The Akka module is considerably simpler because we dropped support for Scala 2.11/2.12 on Kamon 2.8. To simplify the build process we are now compiling with Akka 2.7.1 and Akka HTTP 10.5.3, which come with the BSL license. These are provided dependencies so we will not be bumping the versions our users have in their classpaths.
• Turns out that our Tapir tests were not actually testing anything because of how the tests were written and the instrumentation is not actually working. Needs fixing.
• There was a lot of LLM help in here and I've been going little by little, trying to test every module manually and before moving on to the next. Will do a bigger cleanup once finish migrating all the modules
• I tried importing the build with IntelliJ and Metals and even though the imports succeed, the projects are not really usable. Need to dig deeper into this.