fix: resolve infinite update loop when using createRoot (React 18)

When using React 18's `createRoot` instead of `ReactDOM.render`, two
code paths cause "Maximum update depth exceeded" errors:

1. FallbackListener.componentDidMount calls setState synchronously,
   creating a tight loop: componentDidMount → setState → re-render →
   throw promise → Suspense fallback → componentDidMount → ...
   Fix: defer onStart to a microtask with Promise.resolve().then(),
   breaking the synchronous cycle. Added unmount guard to prevent
   setState after unmount.

2. Keeper uses flushSync to set freeze state, which forces synchronous
   rendering inside createRoot and bypasses React 18's automatic
   batching, amplifying the infinite loop.
   Fix: remove flushSync wrapper — the setTimeout already provides
   the necessary delay.

Closes #336, Closes #257

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

Author: yujiayu02

src/core/Bridge/Suspense.js

@@ -9,10 +9,20 @@ const Lazy = isSupported ? lazy(() => new Promise(() => null)) : () => null
 
 class FallbackListener extends Component {
   componentDidMount() {
-    run(this.props, 'onStart')
+    // Defer onStart to a microtask to break the synchronous render loop
+    // that occurs with React 18's createRoot. Without this, the cycle
+    // componentDidMount → setState → re-render → throw promise → Suspense
+    // fallback → componentDidMount repeats synchronously until React's
+    // max update depth is exceeded.
+    Promise.resolve().then(() => {
+      if (!this._unmounted) {
+        run(this.props, 'onStart')
+      }
+    })
   }
 
   componentWillUnmount() {
+    this._unmounted = true
     run(this.props, 'onEnd')
   }
 

src/core/Keeper.js

@@ -1,5 +1,6 @@
 import React, { PureComponent, Suspense } from 'react'
-import { flushSync } from 'react-dom'
+// flushSync removed — it forces synchronous rendering inside createRoot,
+// bypassing React 18's automatic batching and causing infinite update loops.
 import { get, run, nextTick, EventBus } from 'szfe-tools'
 
 import ReactFreeze from './Freeze'
@@ -103,10 +104,8 @@ export default class Keeper extends PureComponent {
     // 缓存后，延迟冻结，保证各项后续处理得以进行，如关闭弹窗等
     clearTimeout(this.freezeTimeout)
     this.freezeTimeout = setTimeout(() => {
-      flushSync(() => {
-        this.safeSetState({
-          freeze: true,
-        })
+      this.safeSetState({
+        freeze: true,
       })
     }, 1000)
   }