* Fix Qwen Image mask handling
* Fix Qwen attention mask crash with diffusers >=0.37
diffusers v0.37 (PR #12987) optimizes all-ones attention masks to None
in encode_prompt() when there is no padding. This breaks ai-toolkit's
Qwen extensions which call .to() on the mask unconditionally.
Fix: reconstruct the all-ones mask at the boundary (get_prompt_embeds)
right after encode_prompt() returns. This keeps the rest of the code
unchanged and works with both old and new diffusers versions.
Also removes redundant duplicate mask assignments in qwen_image_edit
and qwen_image_edit_plus.
Fixes#740
99a4a5887b