Reduce model picker search rerenders

[cursor]

What Changed

• Split the model picker search field into a small memoized component that owns raw input text locally.
• Added normalizeModelPickerSearchQuery so the parent picker only receives effective search-query changes.
• Added unit coverage for whitespace/case normalization used by model picker ranking.

Why

react-doctor and a manual React hot-spot pass pointed at the model picker/search flow as a UI path worth measuring. With React Scan enabled, typing whitespace into the model search field changed the raw input but not the effective search query, yet ModelPickerContent still re-rendered repeatedly. Keeping raw text local avoids rerendering the full picker/list for no-op query edits while preserving normal filtering for real query text.

UI Changes

React Scan before/after recordings captured in Cursor artifacts:

• Before: react_scan_model_picker_before_whitespace_rerenders.mp4 — typing five spaces increments ModelPickerContent to 20 renders.
• After: react_scan_model_picker_after_whitespace_rerenders.mp4 — typing five spaces keeps ModelPickerContent, ModelListRow, and ModelPickerSidebar at 0 renders.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

Validation:

• corepack pnpm dlx react-doctor@latest . --verbose --category performance --no-telemetry (completed with performance findings used for scan selection)
• corepack pnpm --filter @t3tools/web test -- src/components/chat/modelPickerSearch.test.ts
• NODE_OPTIONS="--experimental-strip-types" corepack pnpm exec vp check
• corepack pnpm exec vp run typecheck

  

Note

Reduce rerenders in model picker search by memoizing input and normalizing queries

• Extracts a new memoized ModelPickerSearchInput component in ModelPickerContent.tsx that wraps ComboboxInput and manages its own raw input state.
• Adds normalizeModelPickerSearchQuery in modelPickerSearch.ts to lowercase and collapse whitespace, publishing upstream state changes only when the normalized value actually differs.
• Escape and Enter key handling are moved into the new component: Escape calls onRequestClose, Enter selects the highlighted model via highlightedModelKeyRef.

^{Macroscope summarized 8481e20.}