Use Kubernetes reccomended labels

[andrii-i]

Description

Currently, jupyter-k8s only sets custom labels (app, workspace.workspaces.jupyter.org/*) on resources. We should adopt Kubernetes recommended labels (https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/) to improve ecosystem tool integration (monitoring, tracking, dashboards), resource discoverability, and consistency with Kubernetes best practices.

Proposed Solution

Add standard app.kubernetes.io/* labels to all operator-managed resources (Workspaces, Deployments, Services, PVCs). See the Kubernetes recommended labels documentation (https://kubernetes.io/docs/concepts/overview/working-with-objects/common-labels/) for the full list of recommended labels and their usage.

Additional context

• feat: WorkspaceTemplate #10 (comment)