story: Platfrom Mesh Core

[Perseus985]

User Story

As an operator of a Platform Mesh instance,
I want to deploy this product in a "Core" edition,
so that resource consumption is kept to a minimum by also allowing the instance to run on smaller clusters while still providing the Platform Mesh Operator, Security Operator (ReBAC and RBAC), and account-operator with their full feature sets.

Acceptance Criteria

• The Core Version can be installed by using Helm values.
• After a fresh installation, the deployment completes with kcp, platform-mesh-operator, security-operator, and account-operator all present and healthy.
• The prerequisites for a successful rollout on a cluster are documented.
• The Core edition is released as part of the normal Platform Mesh releasecycle.
• Everything in the Core Layer works with native Kubernetes RBAC.
• I can bring my own external IdP (OIDC)

Parent Epic

#290

Additional Context

For use in the Opendefense Cloud, infrastructure will exist in several sizes (data centers, deployable/field, mobile).
We want to manage and operate all stacks — across their different sizes — in a uniform way.
As the smallest variant, we only need a "Core" edition with its operators (listed above).