Self-hosted Kura cache nodes with per-account mesh isolation

Customers can now run their own Kura cache nodes inside their own infrastructure while staying connected to the same mutually authenticated mesh as Tuist-managed nodes. The control plane handles tenant-scoped credentials, per-account certificate enrollment, and automatic discovery via heartbeats, so a customer only needs a credential and a URL to deploy a node. You can choose a standalone topology that keeps artifact bytes entirely in your infrastructure, or a bridged topology that pushes self-hosted writes into the managed mesh. This improves cache locality and data residency while preserving the existing security boundaries.