GHSA-vhwf-4x96-vqx2: OpenClaw's skills-install-download can be redirected outside the tools root by rebinding the validated base path

OpenClaw’s skills download installer validated the intended per-skill tools root lexically, but later reused that mutable path while downloading and copying the archive into place. If a local attacker could rebind that tools-root path between validation and the final write, the installer could be redirected to write outside the intended tools directory.

The fix pins the canonical per-skill tools root immediately after validation and derives later download/copy paths from that canonical root, so rebinding the lexical path fails closed instead of redirecting the write.