Select Landmarks

Enables Landmarks selection between two Meshes

/**
 * Node that provides interactive landmark selection on a mesh.
 * 
 * Opens a 3D viewport for selecting corresponding points between
 * meshes, used for mesh fitting and deformation operations.
 * 
 * Usage:
 * 1. Connect mesh input
 * 2. Use viewport to select landmark points
 * 3. Output landmarks for use in fitting nodes
 */