feat(core): restart the backend when the client disconnects

[elkowar]

This is temporary, until we have proper session management and state management -- for now, mainly desirable such that frontend-development doesn't need to manually restart the backend after every change.

[gwimm]

Have you noticed it's not compiling :/

[elkowar]

It is!

[elkowar]

Can you change some more files? I don't think you did enough, I don't feel like this is merge-worthy if someone wants this, they should just re-implement it themselves ~ cpli, someone who wants this