Build CI Toolchain Image / Build & push CI image (push) Failing after 1m42s
Layers the .NET 10 SDK + Node 22 onto our own ersatztv-ffmpeg base (the same COPY --from=.../usr/share/dotnet pattern docker/Dockerfile uses for prod), and bakes the dotnet-ef + reportgenerator global tools the jobs installed per run. Builds/pushes 192.168.1.95:3000/timothy/ersatztv-ci:<sha> via a separate workflow so a ~2GB toolchain image isn't rebuilt on every commit. Refs #390