feat: Add outdated eic-shell warning for singularity/apptainer users

[Copilot]

Users running inside singularity/apptainer have no way to know their outer eic-shell script is stale—there's no automatic update mechanism once it's installed. Add a startup warning when the script can be upgraded.

Changes

• New containers/eic/profile.d/z15_singularity_update.sh: sourced at shell startup; warns when all of the following hold:
  • Shell is interactive
  • Running inside singularity/apptainer ($SINGULARITY_CONTAINER or $APPTAINER_CONTAINER is set)
  • $EIC_SHELL_PREFIX/../eic-shell exists and is writable by the current user
  • That script's mtime is older than 180 days

When triggered, the warning suggests:

WARNING: Your eic-shell script appears to be more than 6 months old.
         Consider upgrading by running outside the container:
           eic-shell --upgrade

The write-access check gates the warning—if the user can't upgrade, there's no point in warning them.

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[Copilot]

Pull request overview

Adds a shell-startup warning inside Singularity/Apptainer containers to help users notice when their outer eic-shell launcher script is likely stale and upgradable.

Changes:

• Introduces a new profile.d startup script that conditionally warns on interactive shells inside Singularity/Apptainer.
• Detects an upgradable outer eic-shell script (exists, writable) and checks whether its mtime is older than ~180 days.
• Prints guidance to run eic-shell --upgrade outside the container when triggered.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 1 comment.

[veprbl]

I hope this works