Review findings from the pilot: the 17-module default import set was
maintained twice (root's array and build-support's userBinary) — drift
would silently make packaged binaries differ from root-built ones. It
now lives once, as build-support.defaultImports; root and userBinary
both draw from it, and root's user-binary wrapper names the shim +
link script through the kernel package like build-support does.
The root aggregate test step likewise duplicated the library domains'
14 test definitions; it now depends on each domain's own standalone
test step (host-only, so root's -Dtarget/-Doptimize deliberately do
not reach them), and the client domain gains an empty test step for
uniformity. Boot-image file list unchanged.
Daniel Samson
15575960bd