Feature/qwen eligen support

[nolan4]

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Pull Request: Add Entity-Level Image Generation (EliGen) for Qwen Image

Summary

This update implements Entity-Level Image Generation (EliGen) for the Qwen Image model, allowing region-specific prompts through spatial masks. The feature provides fine-grained control over image generation by applying separate attention masks for each entity.

Key Features • Spatial attention masking with isolated entity prompts • Automatic mask resizing to match latent dimensions • RoPE embedding implementation aligned with DiffSynth Studio • Support for batch_size > 1 • Backward compatible with standard Qwen Image workflows