Fix: set native user passwords via Hub admin API in manage_users.py

[mariodruiz]

Summary

Fix native user batch onboarding by updating manage_users.py to set passwords through the Hub admin API instead of the legacy
passwords.dbm kubectl path, which no longer matches how the Hub stores credentials. Align multi-node example values with the single-node spawn UI group names and descriptions.

Changes

scripts/manage_users.py (main fix)

• Replace kubectl/passwords.dbm password writes with Hub admin API calls:
• /hub/admin/api/set-password (single user)
• /hub/admin/api/batch-set-password (batch)
• Add per-user fallback if the batch API call fails
• Fix batch result parsing (success / failed / results[])
• Improve generate_password() so auto-generated passwords meet Hub strength rules (upper, lower, digit, special)
• No change to the existing two-step flow: create → set-passwords

runtime/values-multi-nodes.yaml.example

• Align course group labels with values.yaml (TEACHING LABS, DEVELOPMENT ENVIRONMENT, CUSTOM REPOS)
• Add groupOrder for spawn/Home page grouping
• Normalize code-server profile descriptions

runtime/values.yaml

• Minor description tweaks for code-cpu / code-gpu spawn labels

Testing

In Dublin Cluster

Checklist

• Code follows project style guidelines
• Changes are backward compatible
• Tested on local Kubernetes cluster
• Documentation links updated