Add plan for NATS-based deployment service (homelab-deploy) that enables
on-demand NixOS configuration updates via messaging. Features tiered
permissions (test/prod) enforced at NATS layer.
Update prometheus-scrape-target-labels plan to share the homelab.host
module for host metadata (tier, priority, role, labels) - single source
of truth for both deployment tiers and prometheus labels.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
