A module type that was never baked now says so, instead of compiling in secret

Modules:RequirePrebuilt already refused to compile when a package's bundle could not be fetched at install time. The deeper case — a type that is simply touched later, on first access, with no adopted assembly — still slipped into a Roslyn compile, because that path runs through the type's own compile watcher rather than the install lane.

It no longer does. On a require-prebuilt mesh, any trigger that would compile such a type — first access, a release request, a self-heal, a framework-stale rebuild — parks it instead, with one message: which type, which framework identity and architecture the assembly is missing for, which package's bundle publishes it, and how to retry once it lands. Every page of that type renders the reason through the usual compilation-error overlay instead of waiting on a compile that was never going to be allowed, and the park keeps the refusal bounded — no storm, no retry loop, zero compiles started.

Meshes that do not set the flag are unchanged: they compile exactly as before.