Ports Termix's per-host metrics collector logic onto ArchNest's own SSH
connection helpers (not its multi-user/cache/session scaffolding), exposed via
a new authenticated REST endpoint and a dedicated /host-metrics page with
client-side polling.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BbJV5nm8KPVH1oNJYKpnoF
