Add comprehensive support for GGUF quantized Z-Image models and improve component flexibility:
Backend:
- New Main_GGUF_ZImage_Config for GGUF quantized Z-Image transformers
- Z-Image key detection (_has_z_image_keys) to identify S3-DiT models
- GGUF quantization detection and sidecar LoRA patching for quantized models
- Qwen3Encoder_Qwen3Encoder_Config for standalone Qwen3 encoder models
Model Loader:
- Split Z-Image model