Build Failure: agora_rtc_engine compiled against android-31 while dependencies require android-34+

### Version of the agora_rtc_engine

6.5.3

### Platforms affected

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

### Steps to reproduce

1. Create a Flutter project.

2. Add agora_rtc_engine (latest version) to pubspec.yaml.

3. Attempt to run the app on an Android device/emulator.

### Expected results

The plugin should use flutter.compileSdkVersion or have its internal compileSdkVersion bumped to at least 34 to maintain compatibility with modern AndroidX libraries.

### Actual results

Execution failed for task ':agora_rtc_engine:checkDebugAarMetadata'.
> A failure occurred while executing com.android.build.gradle.internal.tasks.CheckAarMetadataWorkAction
> 19 issues were found when checking AAR metadata:
1. Dependency 'androidx.fragment:fragment:1.7.1' requires libraries and applications that
depend on it to compile against version 34 or later of the Android APIs.
:agora_rtc_engine is currently compiled against android-31.

### Code sample

Code sample

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

### Screenshots or Video

Screenshots / Video demonstration

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### Logs

Logs

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

### Flutter Doctor output

Doctor output

```console
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.38.5, on macOS 15.7.3 24G419 darwin-x64, locale en-US)
[✓] Android toolchain - develop for Android devices (Android SDK version 36.1.0-rc1)
[✓] Xcode - develop for iOS and macOS (Xcode 26.2)
[✓] Chrome - develop for the web
[✓] Connected device (5 available)
[✓] Network resources

• No issues found!
```