Context usage view

## Problem
Currently there is no way to know how much of the context memory has been used up by chat. This can lead to issues when chat history is forgotten, lost or gets murky.

## Expected behavior
I have seen the funtionality which compacts/compresses chat history to clear up context memory but without a visual way to see how much is left it can be hard to plan.

I would like to suggest that the chat window have telmetry on a few things visible to the user so that it can be visualized how the ai is using up tokens and context. A similar example would be how roo code or kilo code presents this to the user allowing for better way to preempt and ways to save context before the usage hits limits.

No file, test, or entry point is named in the issue. Start by locating the chat window and existing context-compaction or token-handling functionality; done means providing user-visible telemetry for context usage and remaining capacity.

Written by the indexing model from the issue text.