feat: remember last launch settings (model, sharding, instance type)

[Drifter4242]

Motivation

Saves the last launch settings, so that the next time you run exo it will default to the same launch settings. This is just a small quality of life improvement.

Changes

When you launch it saves the settings to the web browser local storage. When it fills out the model list, it reads the settings and sets the default.

I reviewed, tested and edited the code, but some of the code was written by Claude Opus. I hope that's ok.

Why It Works

See above

Test Plan

Manual Testing

I have two Macbook Studio M3 Ultras, each with 512Gb ram, connected with Thunderbolt 5. I ran Kimi K2 Thinking with MLX Ring and Tensor Split. I ran exo multiple times to confirm that the default works.

Automated Testing

No changes to automated testing.