[Bug] usage_context function reports incorrect context usage percentage

Bug Description
The new usage_context function is not equivalent to the display of context left. I had 69% usage_context in my statusline but only 10% context left

Environment Info

• Platform: darwin
• Terminal: WarpTerminal
• Version: 2.0.71
• Feedback ID: f9ccc038-aefe-49e5-9c06-14c0f935a674

Errors

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<img width="1270" height="254" alt="Image" src="https://github.com/user-attachments/assets/f75d9773-0bd7-4ca6-8cd9-0db96b254a56" />