[Request]: Add directory creation utility to ApplicationRoot

### Feature or enhancement request details

## Feature Description
To make `ApplicationRoot` more practical and prevent runtime errors when managing storage paths, we can introduce a utility method that ensures the root directory exists on disk.

## Proposed Changes
- Add `createDirectoryIfNeeded()` static method to `ApplicationRoot`.
- Automatically create the directory and any intermediate directories if they do not already exist.

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Start at the ApplicationRoot definition and inspect how its storage path is represented and used. Add coverage for an existing directory, a missing directory, and missing intermediate directories; done means the static method creates the complete path without runtime errors.

Written by the indexing model from the issue text.