Add unlimited-memlock support for Kind clusters

Add spec.yml option `security.unlimited-memlock` that configures
RLIMIT_MEMLOCK to unlimited for Kind cluster pods. This is needed
for workloads like Solana validators that require large amounts of
locked memory for memory-mapped files during snapshot decompression.

When enabled, generates a cri-base.json file with rlimits and mounts
it into the Kind node to override the default containerd runtime spec.

Also includes flake8 line-length fixes for affected files.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

stack_orchestrator/constants.py

@@ -39,3 +39,5 @@ node_affinities_key = "node-affinities"
 node_tolerations_key = "node-tolerations"
 kind_config_filename = "kind-config.yml"
 kube_config_filename = "kubeconfig.yml"
+cri_base_filename = "cri-base.json"
+unlimited_memlock_key = "unlimited-memlock"