Improved autolock functionality, relocated styles

[kajusnau]

Description of changes

1. Improved Autolock Functionality:

   • Previously, when inactive for 5 minutes, the screen would dim to low brightness and return to 100% brightness for a moment before locking.
     This behavior should be fixed now - the transition from dimming to the lock screen should now be smooth.
   • Can be tested by letting system idle for 5 minutes or replacing ${builtins.toString cfg.autolock.duration} with desired time in seconds in /modules/desktop/graphics/labwc.config.nix:267.

2. Relocated Styles:

   • Moved the definitions for the lock screen, login screen, and app launcher styles into the dedicated styles directory.

3. Updated Default Lock Behavior:

   • Changed the default lock behavior to use loginctl. Loginctl lock-session behavior is defined in labwc.config lock-event service.

Checklist for things done

• Summary of the proposed changes in the PR description
• More detailed description in the commit message(s)
• Commits are squashed into relevant entities - avoid a lot of minimal dev time commits in the PR
• Contribution guidelines followed
• Ghaf documentation updated with the commit - https://tiiuae.github.io/ghaf/
• PR linked to architecture documentation and requirement(s) (ticket id)
• Test procedure described (or includes tests). Select one or more:
  • Tested on Lenovo X1 x86_64
  • Tested on Jetson Orin NX or AGX aarch64
  • Tested on Polarfire riscv64
• Author has run make-checks and it passes
• All automatic Github Action checks pass - see actions
• Author has added reviewers and removed PR draft status
• Change requires full re-installation
• Change can be updated with nixos-rebuild ... switch

Instructions for Testing

• List all targets that this applies to:
  Lenovo X1

• Is this a new feature

  • List the test steps to verify:
    Can be tested on Lenovo X1 following usual installation or nixos-rebuild ... switch
    To test functionality, check the following:
  • Session locks automatically after screen dims
  • Session lock can be interrupted by user input while screen is dimming
  • Screen dims and transitions to lock screen smoothly without flashing back to full brightness in-between

• If it is an improvement how does it impact existing functionality?
  Listed in the description above.

[johannarautanen]

Tested on Lenovo-X1 (flashed to the SSD) (commit:18140af5da6319c01f9f87909d5c71ab4272d783)
Used the default "5 minute inactive"-time during testing.

Working:

• Session locks automatically after screen dims

• Session lock can be interrupted by user input while screen is dimming

• Screen dims and transitions to lock screen smoothly without flashing back to full brightness in-between

• all other ghaf apps can be launched

• ci-test automation cases ok

No new findings.