fix(deps): pin @tintinweb/pi-subagents to 0.17.0 so fresh installs stay on pi-ai 0.80.x

pi-subagents 0.18.0 requires pi-ai >=0.81.0; with only rpiv-pi's peer
range "*" to go on, a lockfile-less install (as release.mjs performs
during the version bump) floated to 0.18.0 and failed ERESOLVE against
the repo's pinned pi-ai 0.80.6. Pin the root devDependency to the
version the lockfile already carried.