Feature request: Persistent context window indicator in prompt area

Description

It would be helpful to have a small, always-visible context usage indicator near the prompt area (e.g., showing percentage or token count), similar to how the update banner is displayed.

Current behavior

The only way to check context window usage is via Shift+Tab or /status, which interrupts the workflow.

Proposed behavior

A subtle, persistent indicator (e.g., a progress bar or percentage) near the prompt area that shows how much of the context window has been used. This would help users know when to start a new conversation or manually compact, without having to interrupt their flow.