[Feature Request] Expose Fast mode state to statusLine scripts

Bug Description
Feature request: expose Fast mode state to statusLine scripts

The reasoning effort level is available to custom statusLine commands via effort.level in the JSON
input, which is great — I use it to show an effort symbol in my status line. However, Fast mode (toggled
via /fast) is not exposed anywhere a statusLine script can read it: there's no field in the statusLine
JSON, the model.id/display_name don't change, and nothing is written to settings or an env var.

Could you add a field to the statusLine JSON input indicating whether Fast mode is currently ON — e.g. a
top-level fast_mode boolean (or a fast.enabled object)? That would let users surface a persistent
Fast-mode indicator in their status line, just like effort level. It should reflect live mid-session
toggles.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.1.156
• Feedback ID: b4c93cc0-ff66-4d62-89e7-a151c9813c6b

Errors

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