fix: Ensure config directory exists in post-install and pre-remove

[Taywee]

This was causing install to fail for rpm-ostree install.

[github-actions]

Script Analysis

• The changes add XDG_CONFIG_HOME directory handling logic to both post-install.sh and pre-remove.sh scripts
• Follows standard Unix directory conventions for configuration files
• Maintains backward compatibility by falling back to $HOME/.config and then $PWD/.config
• Uses proper conditional checks for environment variable existence

Security Review

• ❗ Directly using $PWD for config directory in fallback case could lead to unintended locations if script is run from unexpected directories
• ⚠️ No validation of XDG_CONFIG_HOME or HOME paths for special characters or path traversal
• Missing error handling if mkdir -p fails
• No cleanup of temporary .config directory in pre-remove.sh

Optimization Suggestions

• Consider moving this directory setup logic into the Nushell scripts themselves for better consistency
• Add error handling and exit on failure for critical directory creation
• Validate environment variables before use to prevent path injection
• Consider using path expand in Nushell for more robust path handling

Overall Quality: 3

[Taywee]

closes #69

[github-actions]

Script Analysis

• The changes add proper configuration directory handling for Nushell execution in package management contexts
• Added set -e for better error handling in the shell scripts
• Implemented a fallback mechanism for XDG_CONFIG_HOME when neither XDG_CONFIG_HOME nor HOME are set
• Maintains cross-platform compatibility by using standard environment variables

Security Review

• ❗ Potential security issue: The fallback to $PWD/.config could create config directories in unexpected locations if the script is run from a world-writable directory
• ⚠️ No input validation on the environment variables before using them in path construction
• The scripts now properly fail-fast with set -e which improves security by preventing partial execution

Optimization Suggestions

• Consider using Nushell's built-in config path handling instead of shell script logic
• Could potentially merge the common directory creation logic into a shared function
• The current implementation is simple and efficient for its purpose

Overall Quality: 4