Multi-box scaling and warm-handoff account moves for bare-metal Tuist Cloud regions

Tuist Cloud regions hosted on bare-metal infrastructure can now scale out to multiple boxes per region instead of being limited to a single box. Customer accounts are routed via per-account DNS records to the specific box hosting their pods, so traffic no longer round-robins across boxes that do not serve the request. Operators can also rebalance an account between boxes in the same region via a warm handoff: the destination box warms up against the source over the account peer plane while the source keeps serving, then ownership is swapped atomically, so users do not see a cold-cache dip or service interruption during the move.