Build reliability fix

A focused release with no product change. It exists so the releases that follow it ship on time.

Builds that finish

• No more random build failures — the tool that compiles Loquent’s styles was fetched from the internet on every build and sometimes did not arrive. It is now baked into the build image, so a release cannot fail on a download.
• Failures say what went wrong — a styling compile that does fail now stops the build immediately with its own message, instead of surfacing minutes later as an unrelated error.