assertEntriesLoaded() flagged ANY fiber-less entry as a failed import, but a
`disabled: true` entry settles without a fiber by design (Entry.refresh() skips
init() when disabled) — a valid "plugin off" config, not a broken import. Both
app bins now filter `fiber === undefined && !entry.disabled`. The stdio built-bin
smoke gains a disabled-(unresolvable)-entry config that must still boot.
The verify-package-paths lib-skip was unconditional and ran before the
moved-package check, so a stale group-less `packages/acp-agent/lib/bin.js` (the
exact drift this gate catches) was silently ignored just for containing `lib`.
Scope the skip: only exempt `lib` when it is the segment after an EXISTING
`packages/<group>/<pkg>` root, so a real-but-unbuilt `lib/bin.js` is still exempt
while a stale package path flags.