feat: Admin-shared files/folders in multi-user Open Terminal mode

[FujinoXiao]

feat: Admin-shared files/folders in multi-user Open Terminal mode

Is your feature request related to a problem? Please describe.

In the built-in multi-user mode (OPEN_TERMINAL_MULTI_USER=true), each user is fully isolated — they can only see files in their own /home/{user-id} directory. This is great for privacy, but there is no way for an administrator to share common files (scripts, datasets, configs, templates, etc.) with all users. Currently, the admin would have to manually copy files into each user's home directory, which doesn't scale.

Describe the solution you'd like

A shared directory mechanism, for example:

• A dedicated path like /shared or /home/shared that is read-only for regular users and writable by administrators.
• Files placed there by the admin appear in every user's file browser, clearly marked as shared (e.g., with a different icon or a "Shared" label).
• Users can reference these shared files in their terminal commands and chat, but cannot modify or delete them.
• Admins can manage the shared space via the file browser or terminal.

Use cases

• Admin provides a set of common utility scripts or config templates for the team.
• Shared datasets or reference documents that all users need to access.
• Company-wide environment files (.env.example, onboarding guides, etc.).

Why not use per-user containers (Terminals)?

Per-user containers (enterprise feature) solve isolation but add complexity and cost. For small teams using the built-in multi-user mode, a lightweight shared folder would cover 80% of the collaboration needs without requiring the enterprise tier.