CV ArUco Board Pose (Average)

Estimates the pose (rotation + translation) of a planar ArUco board by solving each marker's pose independently (cv2.solvePnP, IPPE_SQUARE - exact for a coplanar square) and AVERAGING them: the rotation matrices are meaned then re-orthonormalized via SVD (a valid rotation), the translations meaned to the board centroid. Because every marker lies in the same plane its individual pose already carries the board orientation; averaging cancels per-marker detection noise. The two-fold planar-pose ambiguity is resolved per marker by keeping the solution whose normal faces the camera, so a stray flipped marker cannot corrupt the mean. Feed the rvec/tvec into cv2.projectPoints + 'Draw Polygon' to overlay a 3D object (see the ArUco cube workflow). Zero markers returns found=false with a zero pose instead of erroring - branch on 'found' with a control-flow node.