Wan 2.2 T2V cannot be upcast from FP8 yet I2V works.

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

Like wan I2v, T2V model should be able to be upcast to FP16/FP32/BF16/E5M2, etc.

### Actual Behavior

Regardless of precision, wan T2V weights are always saved in whatever they came with.

### Steps to Reproduce

Put a Load Diffusion model node and unet or model save. Try to change precision of the model. Weights will be the same as they were. In contrast, using the WanI2V model, the weights are cast correctly and change in size.

### Debug Logs

```powershell
none, all look normal.
```

### Other

_No response_