fix(react-router): prevent webpack static analysis of React.use with let binding (#7182)

Author: mixelburg

.changeset/fix-react-router-webpack-use-analysis.md

@@ -0,0 +1,5 @@
+---
+'@tanstack/react-router': patch
+---
+
+fix(react-router): prevent webpack static analysis of `React.use` with let binding

packages/react-router/src/utils.ts

@@ -5,7 +5,8 @@ import * as React from 'react'
 // React 18 with Webpack, which statically analyzes imports and fails when it
 // sees React.use referenced (since 'use' is not exported from React 18).
 // This uses a dynamic string lookup to avoid the static analysis.
-const REACT_USE = 'use'
+// eslint-disable-next-line prefer-const -- Must be `let` to prevent bundler constant-folding
+let REACT_USE = 'use'
 
 /**
  * React.use if available (React 19+), undefined otherwise.