Repository: flutter
Issue: FloatingActionButton is out of frame when trying to place it in CupertinoSheetRoute
Labels: f: material design,f: cupertino,has reproducible steps,team-design,found in release: 3.29

### Steps to reproduce

I wanted to try out [PR](https://github.com/flutter/flutter/pull/157568#issuecomment-2590955571)'s recently implemented CupertinoSheetRoute, so I ran [sheet.dart](https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/cupertino/sheet.dart) and examples' [cupertino_sheet.0.dart](https://github.com/MitchellGoodwin/flutter/blob/1546d7c8d3c86cbb41a482a131dbef552130b106/examples/api/lib/cupertino/sheet/cupertino_sheet.0.dart).
This works fine.
Next, I wanted to add a FloatingActionButton to this code.
CupertinoPageScaffold does not have a floatingActionButton property, so I changed it to Scaffold and placed a floatingActionButton.
However, this code places the floatingActionButton partially outside the frame.


### Expected results

FloatingActionButton should be displayed in the frame in the Sheet.

### Actual results

FloatingActionButton is displayed out of frame in Sheet

### Code sample

<details open><summary>Code sample</summary>

```dart
// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_engineer_codecheck/sheet.dart';

/// Flutter code sample for [CupertinoSheetRoute].

void main() {
  runApp(const CupertinoSheetApp());
}

class CupertinoSheetApp extends StatelessWidget {
  const CupertinoSheetApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const CupertinoApp(title: 'Cupertino Sheet', home: HomePage());
  }
}

class HomePage extends StatelessWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      navigationBar: const CupertinoNavigationBar(
        middle: Text('Sheet Example'),
        automaticBackgroundVisibility: false,
      ),
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            CupertinoButton.filled(
              onPressed: () {
                Navigator.of(context).push(
                  CupertinoSheetRoute<void>(
                    builder: (BuildContext context) => const _SheetScaffold(),
                  ),
                );
              },
              child: const Text('Open Bottom Sheet'),
            ),
          ],
        ),
      ),
    );
  }
}

class _SheetScaffold extends StatelessWidget {
  const _SheetScaffold();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: Icon(Icons.add),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text('CupertinoSheetRoute'),
            CupertinoButton.filled(
              onPressed: () {
                Navigator.of(context).maybePop();
              },
              child: const Text('Go Back'),
            ),
            const Text('You can also close this sheet by dragging downwards'),
            CupertinoButton.filled(
              onPressed: () {
                Navigator.of(context).push(
                  CupertinoSheetRoute<void>(
                    builder: (BuildContext context) => const _SheetScaffold(),
                  ),
                );
              },
              child: const Text('Push Another Sheet'),
            ),
          ],
        ),
      ),
    );
  }
}

```

</details>


### Screenshots or Video

<details open>
<summary>Screenshots / Video demonstration</summary>

| iOS | Android |
|----------|----------|
| <img src="https://github.com/user-attachments/assets/4b99e743-3c9c-42fa-acff-969e404a03f3" width="70%" />  | <img src="https://github.com/user-attachments/assets/61cb69d0-68fc-4a71-945f-699f26a4cd8b" />         | 
</details>


### Logs

_No response_

### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
$ flutter doctor -v
[✓] Flutter (Channel stable, 3.27.1, on macOS 13.5.2 22G91 darwin-arm64, locale ja-JP)
    • Flutter version 3.27.1 on channel stable at /Users/yamamotohiroto/fvm/versions/3.27.1
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 17025dd882 (6 weeks ago), 2024-12-17 03:23:09 +0900
    • Engine revision cb4b5fff73
    • Dart version 3.6.0
    • DevTools version 2.40.2

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    • Android SDK at /Users/yamamotohiroto/Library/Android/sdk
    • Platform android-35, build-tools 35.0.0
    • ANDROID_HOME = /Users/yamamotohiroto/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 21.0.3+-79915917-b509.11)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.2)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15C500b
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.2)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 21.0.3+-79915917-b509.11)

[✓] VS Code (version 1.93.1)
    • VS Code at /Users/yamamotohiroto/Downloads/Visual Studio Code.app/Contents
    • Flutter extension version 3.102.0

[✓] Connected device (5 available)
    • iPhone (mobile)                 • 00008120-000A5D180E01A01E            • ios            • iOS 17.6.1 21G93
    • iPhone 15 (mobile)              • B02EDDD3-93FB-489F-93B1-A8BFA65FD1C3 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-17-0 (simulator)
    • macOS (desktop)                 • macos                                • darwin-arm64   • macOS 13.5.2 22G91 darwin-arm64
    • Mac Designed for iPad (desktop) • mac-designed-for-ipad                • darwin         • macOS 13.5.2 22G91 darwin-arm64
    • Chrome (web)                    • chrome                               • web-javascript • Google Chrome 131.0.6778.267

[✓] Network resources
    • All expected network resources are available.

• No issues found!
```

</details>