Case sensitivity preservation in list_allowed_directories

[jszala]

The list_allowed_directories function currently returns paths in lowercase, even though the filesystem operations respect case sensitivity. This can be confusing when working with case-sensitive paths.

The issue appears to be in how paths are normalized when stored in allowedDirectories, while actual filesystem operations preserve case sensitivity.

Steps to reproduce:

1. Start server with case-sensitive paths like "/home/user/Desktop/"
2. Call list_allowed_directories
3. Observe that the returned paths are lowercase: "/home/user/desktop/"

Suggested fix: Modify path normalization to preserve case in the allowedDirectories array.