Self-hosted Kura cache nodes with per-account mesh CA enrollment

You can now run Kura cache nodes in your own infrastructure while keeping them enrolled in the same mutually authenticated mesh as Tuist-managed nodes. Each account gets its own mesh CA, and self-hosted nodes receive account-scoped credentials issued through the Tuist control plane. Nodes register automatically via heartbeats, bridge their writes into the managed cache through a public peer gateway, and warm themselves from the managed mesh when they join, giving you locality and data residency for cache artifacts without giving up centralized authentication or certificate management.