AR Workspace Safety

The single source of truth for two questions:

1. Where can I write/delete on this machine?
2. How do I run Python and install packages safely?

This skill is independent. Apply it even when the user asks for "just a quick install" or "just delete this".

Default Paths

AR_IN_CC=.
DATA_DISK=.
WORKSPACE=$DATA_DISK/workspace

If $DATA_DISK is unclear, ask once before any destructive action.