Packages had their compiled output checked in next to src/: .js,
.d.ts and cjs/ trees at the package root, 251 symlinks into build/,
root copies of typegen generate/ and templates/ and of types-support
json/, and a LICENSE per package. The build writes all of these into
build/ itself; in the source tree they shadowed src/ for anything
resolving the package root and drifted from it.