Compute the recommended initialization scale for neural network weights.
Xavier (Glorot) initialization — for layers with tanh/sigmoid: $$\text{scale} = \sqrt{\frac{2}{\text{fan\_in} + \text{fan\_out}}}$$
He (Kaiming) initialization — for layers with ReLU: $$\text{scale} = \sqrt{\frac{2}{\text{fan\_in}}}$$
Given fan_in and fan_out dimensions, compute both initialization scales.
Input:
fan_in: number of input units (int) fan_out: number of output units (int) Output: A dict with “xavier_scale” and “he_scale” (both floats).