As an admin, I want a script to configure desktop SSO with LightDM

[guimard]

User Story

As a system administrator,
I want a setup script to configure desktop SSO with LightDM,
So that I can quickly deploy workstations with LLNG authentication.

Acceptance Criteria

• llng-desktop-setup configures LightDM for LLNG SSO
• Installs required packages (lightdm, lightdm-webkit2-greeter)
• Installs LLNG webkit theme
• Configures LightDM and greeter
• Configures PAM for token_mode
• Optional NSS configuration for user resolution

Technical Details

Usage

llng-desktop-setup --portal https://auth.example.com [options]

Options:
  -p, --portal URL        LLNG portal URL (required)
  -c, --client-id ID      OAuth2 client ID (default: desktop-greeter)
  -y, --yes               Non-interactive mode
  -h, --help              Show help

Actions Performed

1. Install dependencies: lightdm, lightdm-webkit2-greeter
2. Install LLNG greeter theme to /usr/share/lightdm-webkit/themes/
3. Configure /etc/lightdm/lightdm.conf.d/50-llng.conf
4. Configure /etc/lightdm/lightdm-webkit2-greeter.conf with portal URL
5. Backup and configure /etc/pam.d/lightdm for token_mode

Component

Repo: llng-pam-module
Files: scripts/llng-desktop-setup (new bash script)