fix(lint): move AssistantSessionRedirect out of router.tsx (react-refresh gate)

react-refresh/only-export-components fires when a file with the
\`router\` const export also defines a component (the redirect helper).
Moves the small helper to its own file under components/routing/ so
HMR can keep the route-component module hot-reload-eligible.

No behavior change.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/components/routing/AssistantSessionRedirect.tsx

@@ -0,0 +1,11 @@
+import { Navigate, useParams } from 'react-router-dom'
+
+/**
+ * Permanent 301-style redirect from /assistant/:sessionId to /pilot/:sessionId.
+ * Used by the Phase 1 route-rename; paired with a bare-path redirect to /pilot.
+ * SPA redirects replace history so the legacy URL does not linger in back-nav.
+ */
+export function AssistantSessionRedirect() {
+  const { sessionId } = useParams<{ sessionId: string }>()
+  return <Navigate to={sessionId ? `/pilot/${sessionId}` : '/pilot'} replace />
+}

frontend/src/router.tsx

@@ -1,4 +1,5 @@
-import { createBrowserRouter, Navigate, useParams } from 'react-router-dom'
+import { createBrowserRouter, Navigate } from 'react-router-dom'
+import { AssistantSessionRedirect } from '@/components/routing/AssistantSessionRedirect'
 import * as Sentry from '@sentry/react'
 import { Suspense } from 'react'
 import { AppLayout, ProtectedRoute } from '@/components/layout'
@@ -102,16 +103,6 @@ function page(Component: React.LazyExoticComponent<React.ComponentType>) {
   )
 }
 
-/**
- * Permanent 301-style redirect from /assistant/:sessionId to /pilot/:sessionId.
- * Used by the Phase 1 route-rename; paired with a bare-path redirect to /pilot.
- * SPA redirects replace history so the legacy URL does not linger in back-nav.
- */
-function AssistantSessionRedirect() {
-  const { sessionId } = useParams<{ sessionId: string }>()
-  return <Navigate to={sessionId ? `/pilot/${sessionId}` : '/pilot'} replace />
-}
-
 export const router = sentryCreateBrowserRouter([
   {
     path: '/landing',