[Bug]: Walking navigation on iOS has some problems

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Description of the bug

Walking navigation on iOS has some problems

### Flutter version

3.38.5

### Package version

0.8.4

### Native SDK versions

- [x] I haven't changed the version of the native SDKs

### Flutter Doctor Output

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.38.5, on macOS 26.4.1 25E253 darwin-arm64, locale en-FR)
[✓] Android toolchain - develop for Android devices (Android SDK version 36.1.0)
[✓] Xcode - develop for iOS and macOS (Xcode 26.4)
[✓] Chrome - develop for the web
[✓] Connected device (5 available)
[✓] Network resources

### Steps to reproduce

With the example app on iOS (device or simulator):

OK = camera is following mode
KO = no camera updated to center to the user → no following mode

1. Go to the navigation page
2. Switch to walking mode
3. Click on the map, then add a waypoint

Then I try with some settings for followMyLocation in the _startGuidedNavigation function:

- With followMyLocation(CameraPerspective.tilted) or without followMyLocation:

1. Start guidance → KO
2. Change camera position (by gesture), then click on recenter → KO
3. Click on compass → OK
4. Change camera position (by gesture), then click on recenter → OK

- With CameraPerspective.topDownNorthUp:

1. Start guidance → OK
2. Change camera position (by gesture), then click on recenter → OK
3. Change camera position (by gesture), then click on compass, then click on recenter → OK
4. Click on compass, then change camera position (by gesture), then click on recenter → KO

- With CameraPerspective.topDownHeadingUp:

1. Start guidance → KO
2. Change camera position (by gesture), then click on recenter → KO
3. Click on compass → KO
4. Click on compass → OK
5. Change camera position (by gesture), then click on compass, then click on recenter → KO
6. Click on compass, then change camera position (by gesture), then click on recenter → KO

⚠️ Even when I say OK for topDownHeadingUp, I never get a valid heading direction

100% reproducible

Tested on:
- Real device: iPhone 13 mini (iOS 16.2)
- Simulator: iPhone 17 (iOS 16.4)

Here is my understanding of the current logic:
- When the camera is centered on the user, clicking on compass changes the perspective between tilted and topDownNorthUp
- When the camera is not centered on the user, clicking on it:
- does nothing in topDownNorthUp
- works only once in tilted mode
- When clicking on recenter:
- it works in topDownNorthUp
- it does nothing in tilted or topDownHeadingUp

Is this a bug in the native iOS library?
Any idea how to fix this?

### Expected vs Actual Behavior

Click on a button (re-center / compass) should always do something :)

### Code Sample

```dart
Future _startGuidedNavigation() async {
assert(_navigationViewController != null);
if (!_navigatorInitialized) {
await _initializeNavigator();
}
await _navigationViewController?.setNavigationUIEnabled(true);
await _startGuidance();
// test 1 : await _navigationViewController?.followMyLocation(CameraPerspective.tilted);
// test 2 : await _navigationViewController?.followMyLocation(CameraPerspective.topDownNorthUp);
// test 3 : await _navigationViewController?.followMyLocation(CameraPerspective.topDownHeadingUp);
}
```

### Additional Context

_No response_