Enhancement: Add a tokens per second field in the model selection hover

Currently, I can see the cost, context length, reasoning levels info when I hover over a model name in the model selector. I would love to be able to also see the speed of the model specially when I am running simple tasks, I want to choose the fastest model out there.

Start at the model selector hover UI and trace how cost, context length, and reasoning-level information are supplied. Identify the available source for tokens-per-second data, display it alongside the existing fields, and verify that speed information appears when hovering over a model.

索引モデルが issue の本文から書いたものです。