Raise per-node RAM from 16 GiB to 24 GiB for proper failover headroom.
Matches the live rolling resize of the three k3s-dev VMs on Proxmox
(qm set --memory 24576 per node, one at a time, KSM enabled first).
Single memory_mib var applies to all three nodes via for_each, so a
future `tofu apply` would resize all three at once and break etcd
quorum — the resize MUST be done live/rolling, not via apply.
Co-Authored-By: Claude Opus 4.8 <[email protected]>