Add React Scan project grouping recordings

Co-authored-by: Julius Marminge <juliusmarminge@users.noreply.github.com>

Author: cursoragent

artifacts/react-performance/README.md

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+React performance scan artifacts for the project grouping selector fix.
+
+- `before-react-scan-project-grouping.webm`: before the fix, captured with React Scan injected before React mounts.
+- `after-react-scan-project-grouping.webm`: after the fix, captured with the same authenticated navigation flow.
+
+Capture flow:
+
+1. Start the web dev server with React Scan injected through Playwright `addInitScript`.
+2. Pair against a clean local server home.
+3. Open `/`, navigate to `/settings/general`, then return to `/`.
+
+The fix stabilizes the project grouping settings selector shared by Sidebar, ChatView, root event routing, and new-thread creation so unrelated parent renders reuse the same grouping object instead of invalidating downstream memoized project derivations.