load_sparsectrl and load_svdcontrolnet never set controlnet_config["dtype"],
so the control model was built with dtype=None (float32) while the UNet runs
in fp16. This caused "mat1 and mat2 must have the same dtype, but got Half and
Float" at sampling time (notably for .pth/.ckpt SparseCtrl models).
Set controlnet_config["dtype"] = unet_dtype before building the model, matching
the existing ControlNet++ and CtrLoRA loaders and ComfyUI's own controlnet loader.
Fixes#574
Amp-Thread-ID: https://ampcode.com/threads/T-019e947a-9fd3-76df-a847-5eb68d7f18de
Co-authored-by: Amp <amp@ampcode.com>