fix: move Date.now() out of render in ErrorBoundary to satisfy eslint purity rule

The chunk-reload logic used Date.now() and sessionStorage during render,
triggering react-hooks/purity. Moved to useEffect so side effects run
after commit, fixing the CI lint failure.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/common/ErrorBoundary.tsx

@@ -1,5 +1,5 @@
 import * as Sentry from '@sentry/react'
-import { type ReactNode } from 'react'
+import { type ReactNode, useEffect, useRef } from 'react'
 import { Button } from '@/components/ui/Button'
 
 interface FallbackProps {
@@ -18,17 +18,20 @@ function isChunkLoadError(error: Error): boolean {
 }
 
 function DefaultFallback({ error, resetError }: FallbackProps) {
+  const reloadingRef = useRef(false)
+
   // Auto-reload on stale chunk errors (happens after deployments)
-  if (isChunkLoadError(error)) {
+  useEffect(() => {
+    if (!isChunkLoadError(error)) return
     const key = 'rf_boundary_chunk_reload'
     const lastReload = sessionStorage.getItem(key)
     const now = Date.now()
     if (!lastReload || now - Number(lastReload) > 10_000) {
       sessionStorage.setItem(key, String(now))
+      reloadingRef.current = true
       window.location.reload()
-      return null
     }
-  }
+  }, [error])
 
   return (
     <div className="flex min-h-[400px] flex-col items-center justify-center p-8">