[BLCCoreStudio]

Summary

Upgrades concept/containers from a short schema-v1 overview into a schema-v3 deep technical reference.

Changes

• explain the process-isolation mental model instead of treating containers as lightweight VMs
• cover Linux namespaces, cgroup v2, capabilities, seccomp, user namespaces, filesystems, storage, networking, signals, observability, performance, reliability, and security boundaries
• separate image, registry, runtime, and container concepts
• explain OCI Image, Runtime, and Distribution standards
• add Kubernetes CRI context so orchestration and runtime layers are not conflated
• add Technology Universe coverage metadata
• add deliberate graph relationships to the Linux kernel, Docker, containerd, Podman, and Kubernetes
• expand the source set to primary standards and authoritative platform documentation
• record the deep-dive review in module history

Quality bar

This follows the same principle as the Git and Docker flagship modules without copying their structure mechanically: the module is organized around the stable container mental model and trust boundaries that matter for this subject.

All candidate files remain text-only entry/* data and should be validated by the trusted module-PR workflow merged into main.