Validate external app dependencies and bootstrap them if not present.

[Art9681]

Eternal will require third party application installations for the various tools that will not be embedded. Currently, the web tool requires a headless Chrome install. Chromium would be ideal but it has not been tested yet. We need a method to detect if this app is installed in the end user's OS, and if not, install it.

The Go ChromeDP package may have methods to do this. Otherwise we will implement our own.

If its possible to do this via the package, then the implementation should go in the web tool:

https://github.com/intelligencedev/eternal/blob/main/pkg/web/web.go

Otherwise, a generic method in the main app will suffice to run the process for any third party dependency.

[Art9681]

This is almost complete as intended. We just need to bootstrap the ComfyUI backend automagically during application startup. All of the code is staged to make this happen. This is also slated for #75