Write a complete SwiftUI view for visionOS 26 that presents a fully immersive space when a button is tapped.

The view must:
1. Have a button labeled "Enter Immersive Space".
2. Use the `@Environment(\.openImmersiveSpace)` and `@Environment(\.dismissImmersiveSpace)` variables.
3. Be able to open an immersive space with the ID "MyImmersiveScene".
4. Include a second button inside the immersive space to dismiss it.