Add BackHandler to dismiss LogBox toasts on back press

Summary:
On Android, pressing the hardware back button while LogBox notification toasts or the full inspector overlay are visible has no effect on the JS side. The only way to dismiss notifications is the on-screen X button, and the only way to close the inspector is via Minimize/Dismiss.

This adds `BackHandler` listeners to both JS containers:

**Notification toasts**: A new `LogBoxNotificationBackHandler` component mounts alongside the toasts and registers a `hardwareBackPress` listener that calls `clearWarnings()` + `clearErrors()`, equivalent to pressing X on every visible toast. The component returns null and auto-cleans the listener on unmount.

**Inspector overlay**: `LogBoxInspectorContainer` registers a `hardwareBackPress` listener in `componentDidMount` that calls `_handleMinimize()` (`setSelectedLog(-1)`), closing the overlay non-destructively — same as pressing the Minimize button.

Changelog: [Android][Added] - Allow LogBox notification toasts and inspector overlay to be dismissed via Android back button

Differential Revision: D101178179

Author: Abbondanzo

packages/react-native/Libraries/LogBox/LogBoxInspectorContainer.js

@@ -12,6 +12,7 @@ import type LogBoxLog from './Data/LogBoxLog';
 
 import View from '../Components/View/View';
 import StyleSheet from '../StyleSheet/StyleSheet';
+import BackHandler from '../Utilities/BackHandler';
 import * as LogBoxData from './Data/LogBoxData';
 import LogBoxInspector from './UI/LogBoxInspector';
 import * as React from 'react';
@@ -23,6 +24,27 @@ type Props = Readonly<{
 }>;
 
 export class _LogBoxInspectorContainer extends React.Component<Props> {
+  _backHandler: ?{remove: () => void, ...} = null;
+
+  componentDidMount() {
+    this._backHandler = BackHandler.addEventListener(
+      'hardwareBackPress',
+      () => {
+        if (this.props.selectedLogIndex < 0) {
+          return false;
+        }
+        this._handleMinimize();
+        return true;
+      },
+    );
+  }
+
+  componentWillUnmount() {
+    if (this._backHandler) {
+      this._backHandler.remove();
+    }
+  }
+
   render(): React.Node {
     return (
       <View style={StyleSheet.absoluteFill}>

packages/react-native/Libraries/LogBox/LogBoxNotificationContainer.js

@@ -11,6 +11,7 @@
 import SafeAreaView from '../../src/private/components/safeareaview/SafeAreaView_INTERNAL_DO_NOT_USE';
 import View from '../Components/View/View';
 import StyleSheet from '../StyleSheet/StyleSheet';
+import BackHandler from '../Utilities/BackHandler';
 import * as LogBoxData from './Data/LogBoxData';
 import LogBoxLog from './Data/LogBoxLog';
 import LogBoxLogNotification from './UI/LogBoxNotification';
@@ -22,6 +23,31 @@ type Props = Readonly<{
   isDisabled?: ?boolean,
 }>;
 
+function LogBoxNotificationBackHandler({
+  logs,
+}: {
+  logs: ReadonlyArray<LogBoxLog>,
+}): React.Node {
+  const logsRef = React.useRef(logs);
+  logsRef.current = logs;
+
+  React.useEffect(() => {
+    const subscription = BackHandler.addEventListener(
+      'hardwareBackPress',
+      () => {
+        if (logsRef.current.length === 0) {
+          return false;
+        }
+        LogBoxData.clearWarnings();
+        LogBoxData.clearErrors();
+        return true;
+      },
+    );
+    return () => subscription.remove();
+  }, []);
+  return null;
+}
+
 export function _LogBoxNotificationContainer(props: Props): React.Node {
   const {logs} = props;
 
@@ -60,6 +86,7 @@ export function _LogBoxNotificationContainer(props: Props): React.Node {
   );
   return (
     <SafeAreaView style={styles.list}>
+      <LogBoxNotificationBackHandler logs={logs} />
       {warnings.length > 0 && (
         <View style={styles.toast}>
           <LogBoxLogNotification