Fix Apple camera preview orientation

[jfversluis]

Summary

• Resolve iOS/MacCatalyst camera preview orientation from the active UIWindowScene instead of relying on UIDevice.CurrentDevice.Orientation during preview layout.
• Use EffectiveGeometry.InterfaceOrientation on iOS/MacCatalyst 26+ and UIWindowScene.InterfaceOrientation below that, with fallback to device orientation/last known/portrait when scene orientation is unavailable.
• Register orientation notifications idempotently on connect and remove them on disconnect/dispose; notification handling now requests layout instead of calling LayoutSubviews() directly.

Fixes #40.

Validation

• dotnet restore ZXing.Net.MAUI/ZXing.Net.MAUI.csproj
• dotnet build ZXing.Net.MAUI/ZXing.Net.MAUI.csproj -f net10.0-ios -c Release --no-restore
• dotnet build ZXing.Net.MAUI/ZXing.Net.MAUI.csproj -f net10.0-maccatalyst -c Release --no-restore
• Verified the same iOS/MacCatalyst builds with SDK 10.0.102 selected from a session-local global.json.
• dotnet test ZXing.Net.MAUI.Tests/ZXing.Net.MAUI.Tests.csproj -f net10.0 -c Release

Remaining risk

• Not device-tested in this environment; validation is compile/test coverage only.

Linked issues

Fixes #296.

[jfversluis]

@bstadick since you authored the earlier orientation PR (#186), and @bhuvan94 since you opened the linked issue (#40): could you please test the artifacts from this PR if they help your situation?

This is a fresh, focused iOS/MacCatalyst preview-orientation fix based on current main, without the unrelated workflow changes from the older PR. Any real-device feedback, especially around rotation and iPad/windowed scenarios, would be very helpful.