Native debugger

We can use https://codeberg.org/slembcke/debugger.lua to integrate a native debugger into Astra. It does need some modifications to match it with Astra in general, but it is a really good debugger.

Start by reading debugger.lua from the linked Codeberg project and reviewing Astra's runtime integration points. Identify the modifications needed to match Astra, then verify that the native debugger integrates successfully with the runtime and its debugging workflow.

Written by the indexing model from the issue text.