Feature request: persistent context window status line

Feature Request

Add a persistent status line/bar that always shows context window usage (% used, tokens consumed/available).

Current behavior

Context usage is only visible via the /context command, which must be manually invoked each time.

Desired behavior

A persistent status line (bottom of terminal, or inline after each response) showing:

• Context window % used
• Token count (e.g., 11k/200k (6%))
• Optionally: breakdown by category (system, memory, messages, free)

Why this matters

When working on long sessions or large codebases, it's easy to hit context limits unexpectedly. A persistent indicator would let users:

• Proactively manage context before hitting limits
• Understand how much room remains for complex operations
• Decide when to start a new session

Alternatives considered

• tmux status bar: not feasible because context data isn't exposed outside the session
• Keybinding for /context: works but still requires manual invocation
• Shell prompt integration: same problem — no external API for token counts