AI should provide default filenames (so you never see an "Untitled.ipynb" again)

[ctcjab]

Problem

A user writes,

I'm really digging how AI chat interfaces automatically use an LLM to name your chats in the sidebar. Is there anything like that for Jupyter? I'm sick of coming up with names for my notebooks.

Proposed Solution

While the user is editing a new unsaved notebook, periodically ask the configured LLM to suggest a good filename for it, which is used as a better default filename instead of the current "Untitled(N).ipynb".

Once the user has explicitly saved the new notebook for the first time (whether by clicking "save", or as part of a "close" in response to the "Save your work" modal), and the user has had a chance to explicitly accept (or change) the suggested filename, no further filename suggestions for the notebook need to be generated.