Resolves and returns the default initial Model3DView for this annotation.

The PDF specification allows the default view to be specified in multiple places and using different forms (for example, by name or by index). This method encapsulates the logic to find and return the effective default view that should be used when the annotation is activated.

Typical resolution behavior:

• Inspect annotation-level settings that explicitly identify a default view.
• If not found, inspect the associated 3D stream(s) for a named or indexed default view.
• If the default is specified by name, the view with a matching Name is returned.
• If specified by index, the view at that index in the stream's view list is returned.

If no explicit default view is defined or the referenced view cannot be resolved, the method returns null.