[EPIC] Kubeflow Workspaces standalone deployment

### Certification

- [x] I certify I am an Epic Owner for Kubeflow Notebooks 2.0 and expected to create planning-related issues.

### User Story

As a **platform administrator**, I want to deploy Kubeflow Workspaces as a **self-contained, standalone application**, _without_ requiring the Kubeflow Community Distribution or the Central Dashboard so that I can offer interactive development environments to my users with a smaller operational footprint, managing namespaces, authentication, and access on my own terms rather than adopting the entire Kubeflow platform.

No files, tests, or entry points are named. Start by defining the standalone deployment boundaries for namespaces, authentication, and access, then map the existing Kubeflow Notebooks deployment to identify what depends on the Community Distribution or Central Dashboard. Done means a reviewed implementation plan and acceptance criteria for a self-contained Workspaces application.

Written by the indexing model from the issue text.