Add guarded Intel XPU support alongside CUDA:
- get_device_list now includes xpu:N when available
- device selection (model/text encoder) considers CUDA or XPU and validates devices
- DisTorch donor/offload selection includes xpu devices
Also: remove unused MergeFluxLoRAs node and mapping; delete tools/ and precompiled_binaries/; bump project version to 1.8.1.