Security Hotfix

This release fixes GHSA-vgj6-hcf2-fqf6, a path traversal / RBAC bypass in Headscale rename API calls.

Headplane now URL-encodes user-controlled node and user rename path segments before sending requests to Headscale. This prevents crafted rename values containing path traversal sequences from escaping the intended Headscale API endpoint.

Users running Headplane 0.6.2 or earlier should upgrade to 0.6.3.