A thin, nonconducting plastic rod is bent into a semicircle of radius \(R\) centered at the origin. The rod carries a non-uniform linear charge density given by \(\lambda(\theta) = \lambda_0 \sin\theta\), where \(\lambda_0\) is a positive constant and \(\theta\) is the angle measured counterclockwise from the positive \(x\)-axis (\(0 \le \theta \le \pi\)). Assuming the electric potential is zero at infinity, what is the electric potential at the origin?