fix(app): place context tracker right of model selector

[smsunarto]

Human comments

What was wrong

The follow-up composer's context-window indicator mounted in the external footer's right-anchored group, after the permission picker. Each time it appeared or disappeared it pushed the permission picker sideways — a visible layout shift in a row meant to be stable.

What changed

apps/app/src/components/promptbox/FollowUpPromptBox.tsx: ThreadContextWindowIndicator moved from the external footer's right group into footerStart, immediately after ExecutionControls (the model/reasoning picker). footerStart renders in the prompt box action row's left-anchored flex-1 group, so the indicator now consumes flexible space to the right of the model selector: mounting or unmounting it moves nothing — the + menu and model chip sit to its left, and the voice/submit group is right-anchored separately. The external footer's right group now contains only the permission picker. Hidden-in-compact behavior is unchanged (the indicator lives in the data-promptbox-expanded-only group, matching the prior footer-hidden behavior).

No wire, CLI, or doc changes.

Before / After

Before: tracker at the far right of the footer, after the permission picker.

After: tracker right of the model selector, inside the box.

How you verified

• pnpm exec turbo run typecheck --filter=@bb/app — pass
• pnpm exec turbo run lint --filter=@bb/app — 0 errors
• Unit tests: 152 pass — FollowUpPromptBox.test.tsx (34), ExecutionControls.test.tsx (5), PromptBoxInternal.test.tsx (113)
• Live dev instance: accessibility snapshot of the composer shows Provider, model and reasoning → Context window 13% used adjacent inside the box, and the model selector's bounding-box x-position is identical (481px) on a thread with the indicator and one without it. Before/after composer screenshots were captured: before, the indicator sat at the footer's far right after "Accept Edits"; after, it sits inside the box right of the model chip.

AGENT GENERATED