discoverAgents sorted the listOmpExtensionRoots result by level, which
demoted CLI-injected roots (hard-coded level user) below any project
extensions: settings entry. The sibling skills/hooks/tools surface in
discovery/omp-plugins.ts consumes the returned order verbatim, so an
explicit --extension override could run a different agent than the rest
of its own plugin surface.
Drop the sort and append roots in returned order. Refresh the
discoverAgents doc comment to document the source-precedence chain (CLI
> project settings > user settings > installed plugins) and add a
regression test where a CLI-injected extension wins over a project
extensions: settings extension that defines the same agent name.
Fixes#3920
roboomp
cff8f22d61