Support system revamp

[kparasch]

This branch revamps the support-system misalignment model to resolve support and element poses in 3D, using element-center reference positions and matrix-composed rotations instead of scalar yaw/pitch interpolation. It is based on scipy.spatial.transform.Rotation class.
Allows also to model shrinkage/expansion of supports through the appropriate dz transformations.

Key changes:

• Adds pySC.core.transformations for AT/pySC rotation helpers, vector alignment, and XSuite angle conversion.
• Updates support offsets to use 3D local offsets [dx, dy, dz].
• Computes support and element poses from design reference geometry, including nested support propagation.
• Adds (optional) rigid support behavior that preserves endpoint chord length after endpoint offsets.
• Updates misalignment application to use center rotation anchors.
• Adds an AT load-time warning when the input lattice already contains nonzero element transform fields (dx, dy, dz, tilt, pitch, yaw, tilt_frame), since pySC support updates may overwrite them on touched active-ring elements.