In iOS 26, the device's volume adjustment becomes unavailable when I call enableLocalAudio(false).

### Version of the agora_rtc_engine

6.5.3

### Platforms affected

- [ ] Android
- [x] iOS
- [ ] macOS
- [ ] Windows
- [ ] Web

### Steps to reproduce

1. Initialize the agoraEngine and start a voice call.
2.Join the voice call and call enableLocalAudio(false).

As far as I’ve investigated, volume adjustment works normally if enableLocalAudio(false) is not called.

### Expected results

Even when enableLocalAudio(false) is called, it is still possible to hear other users’ voices, so it is desirable for the device’s volume control to remain functional as usual.

### Actual results

The device's volume adjustment becomes unavailable.
Pressing the side buttons does not change the volume, and the slider in the control panel does not work either.

### Code sample

Code sample

```dart
[Paste your code here]
```

### Screenshots or Video

Screenshots / Video demonstration

[Upload media here]

### Logs

Logs

```console
[Paste your logs here]
```

### Flutter Doctor output

Doctor output

```console
[✓] Flutter (Channel stable, 3.35.6, on macOS 15.2 24C101 darwin-arm64, locale ja-JP) [354ms]
• Flutter version 3.35.6 on channel stable at /Users/harukaoki/fvm/versions/3.35.4
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 9f455d2486 (9 days ago), 2025-10-08 14:55:31 -0500
• Engine revision d2913632a4
• Dart version 3.9.2
• DevTools version 2.48.0
• Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-lldb-debugging

[✓] Android toolchain - develop for Android devices (Android SDK version 36.1.0-rc1) [1,345ms]
• Android SDK at /Users/harukaoki/Library/Android/sdk
• Emulator version 36.1.9.0 (build_id 13823996) (CL:N/A)
• Platform android-36, build-tools 36.1.0-rc1
• Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
This is the JDK bundled with the latest Android Studio installation on this machine.
To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
• Java version OpenJDK Runtime Environment (build 21.0.7+-13880790-b1038.58)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.2) [1,075ms]
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 16C5032a
• CocoaPods version 1.16.2

[✓] Chrome - develop for the web [8ms]
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2025.1) [7ms]
• 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 21.0.7+-13880790-b1038.58)

[✓] VS Code (version 1.103.2) [6ms]
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.112.0

[✓] Connected device (3 available) [6.3s]
• iPhone (8) (wireless) (mobile) • 00008140-001E70D02622801C • ios • iOS 26.0.1 23A355
• macOS (desktop) • macos • darwin-arm64 • macOS 15.2 24C101 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 141.0.7390.77
! Error: Browsing on the local area network for iPhone (8). Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)
! Error: Browsing on the local area network for iPad (3). Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)
! Error: Browsing on the local area network for iPad. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)

[✓] Network resources [338ms]
• All expected network resources are available.

• No issues found!
```