v3.1.0

Changes

• Breaking-ish: Removed deprecated LogQuaternionBSpline class. Use LogQuaternionInterpolation or ModifiedLogQuaternionInterpolation instead.
• Fix: Quaternion.to_axis_angle now returns the canonical form with angle in [0, π], handling the negative-scalar branch correctly.
• Examples: Added Frenet-frame spiral examples for LQI (examples/lqi_spiral_frenet_ex.py) and mLQI (examples/mlqi_spiral_frenet_ex.py).
• Deps: Added examples dependency group with PyQt6 for matplotlib interactive backend.

Full Changelog: v3.0.1...v3.1.0