fix(security): run self-managed images and bootstrap workloads as non-root

[sbaum1994]

Problem

Self-managed NVCF needs its distributed containers and generated worker init containers to run as non-root by default. OCI image metadata and Kubernetes security contexts are separate controls: a pod can run as non-root while its image still has an unset Config.User and is reported as root by an image scanner.

The NVCF scope includes core service images, dependencies, and helper images used by the current self-managed stack. The Cassandra runtime and migration path was hardened in #1712.

Out of scope

The following images appear in the source inventory but are not owned by NVCF and are not built or distributed by this repository's self-managed stack:

• ddcs-dist-kv
• gxcache-service
• gxcache-webhook
• gxcache-init
• streaming-proxy

This issue does not require changes to these images.

Implementation plan

• fix(worker-init): declare a non-root OCI image user #2072: set an explicit non-root user in the worker-init image and verify image metadata.
• fix(nvca): run generated worker init containers as non-root #2073: align generated function and task init containers, trust installation, and shared-volume permissions.
• fix(security): run chart-managed bootstrap workloads as non-root #2084: harden NATS, OpenBao hooks, API Keys, and Kubernetes helper Jobs in their owning charts and image build.
• fix(images): publish non-root defaults for mirrored stack images #2085: publish non-root OCI defaults for mirrored dependency and helper images, then advance the owning stack pins and inventory.
• test(self-managed): validate non-root bootstrap in both cluster modes #2074: validate fresh installs, upgrades, and worker behavior with both single-cluster and multi-cluster Helmfile setups.

Acceptance criteria

• Every NVCF-owned released image in scope declares a numeric non-root OCI user, and its rendered workload explicitly uses a compatible non-root security context.
• Generated worker init containers can read configuration and write required shared files without root privileges.
• Cassandra migration hooks remain non-root.
• Both Helmfile topologies render and install successfully, including relevant migration and bootstrap hooks.
• Image metadata and runtime execution are verified separately against released digests.