Add text field masking API (occludeAllTextFields)

## Description
Add API to automatically mask all text input fields on specified screens.

## API
```kotlin
fun occludeAllTextFields(screens: List<String>? = null)
```

## Platforms
- Android: `UXCamOccludeAllTextFields` occlusion helper
- iOS: `UXCam.occludeAllTextFields()`

## Use Case
- Automatically protect all text inputs without manual tagging
- Apply to specific screens or globally