Add Kubernetes resilience suite

[Osvaldo Andrade (osvaldoandrade)]

Summary

• add a Kubernetes RF=3 resilience suite with dry-run and live modes
• document the acceptance matrix for pod, node, orphan-process, disk, network, and quorum-loss faults
• add a nightly GitHub Actions dry-run gate with artifact upload

Validation

• /bin/bash -n scripts/k8s_resilience_suite.sh
• MODE=dry-run ARTIFACT_DIR=/tmp/cefas-resilience/pr575 scripts/k8s_resilience_suite.sh
• scripts/test_helm_resilience.sh
• ruby -e 'require "yaml"; YAML.load_file(".github/workflows/resilience-nightly.yml")'
• go test ./...

Closes #575.
Closes #590.
Closes #597.
Closes #598.