Rodrigues Rotation Formula

Implement Rodrigues' rotation formula to rotate a 3D point around an arbitrary axis.

Given axis $\mathbf{k}$ (unit vector) and angle $\theta$, the rotated point is:

$\mathbf{v}_{rot} = \mathbf{v}\cos\theta + (\mathbf{k} \times \mathbf{v})\sin\theta + \mathbf{k}(\mathbf{k} \cdot \mathbf{v})(1 - \cos\theta)$

This decomposes as:

1. Component parallel to axis (unchanged by rotation)
2. Component perpendicular to axis (rotated in the plane)

Used in camera pose estimation, 3D reconstruction, and robotics.