Add modern ControlNet inpainting support

examples/qwen_image_inpainting/README.md

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+# Qwen Image ControlNet inpainting
+
+This reviewer example adapts the active inpainting branch of ComfyUI's official
+Qwen Image workflow. It uses **Load Advanced ControlNet Model** and **Apply
+Advanced ControlNet Inpainting**, while retaining the official Qwen base
+pipeline and the bypassed optional Lightning LoRA. Node titles are left at
+their ComfyUI defaults; the workflow stores no node title overrides.
+
+## Inputs and models
+
+Download the official inputs to `ComfyUI/input` with these exact names:
+
+- [`acn_qwen_inpaint_source.png`](https://huggingface.co/InstantX/Qwen-Image-ControlNet-Inpainting/resolve/main/assets/images/image1.png)
+- [`acn_qwen_inpaint_mask.png`](https://huggingface.co/InstantX/Qwen-Image-ControlNet-Inpainting/resolve/main/assets/masks/mask1.png)
+
+The model author's repository is
+[`InstantX/Qwen-Image-ControlNet-Inpainting`](https://huggingface.co/InstantX/Qwen-Image-ControlNet-Inpainting).
+Download every model below to the listed folder under `ComfyUI/models`:
+
+| File and exact download | Folder |
+| --- | --- |
+| [`qwen_image_fp8_e4m3fn.safetensors`](https://huggingface.co/Comfy-Org/Qwen-Image_ComfyUI/resolve/main/split_files/diffusion_models/qwen_image_fp8_e4m3fn.safetensors) | `diffusion_models` |
+| [`qwen_2.5_vl_7b_fp8_scaled.safetensors`](https://huggingface.co/Comfy-Org/Qwen-Image_ComfyUI/resolve/main/split_files/text_encoders/qwen_2.5_vl_7b_fp8_scaled.safetensors) | `text_encoders` |
+| [`qwen_image_vae.safetensors`](https://huggingface.co/Comfy-Org/Qwen-Image_ComfyUI/resolve/main/split_files/vae/qwen_image_vae.safetensors) | `vae` |
+| [`Qwen-Image-InstantX-ControlNet-Inpainting.safetensors`](https://huggingface.co/Comfy-Org/Qwen-Image-InstantX-ControlNets/resolve/main/split_files/controlnet/Qwen-Image-InstantX-ControlNet-Inpainting.safetensors) | `controlnet` |
+| [`Qwen-Image-Lightning-4steps-V1.0.safetensors`](https://huggingface.co/lightx2v/Qwen-Image-Lightning/resolve/main/Qwen-Image-Lightning-4steps-V1.0.safetensors) | `loras` (optional and bypassed) |
+
+## Run
+
+1. Download the two inputs and five model files to the folders above.
+2. Load `qwen_image_inpainting.json` in ComfyUI.
+3. Queue the workflow unchanged.
+
+For command-line input reproduction:
+
+```sh
+curl -L https://huggingface.co/InstantX/Qwen-Image-ControlNet-Inpainting/resolve/main/assets/images/image1.png -o ComfyUI/input/acn_qwen_inpaint_source.png
+curl -L https://huggingface.co/InstantX/Qwen-Image-ControlNet-Inpainting/resolve/main/assets/masks/mask1.png -o ComfyUI/input/acn_qwen_inpaint_mask.png
+```
+
+The unchanged example uses seed `134554158057228` (fixed), 20 steps, CFG 2.5,
+Euler, the simple scheduler, denoise 1.0, model shift 3.1, control strength 1.0,
+and control start/end 0.0/1.0. Its prompt is `The Queen, on a throne,
+surrounded by Knights, HD, Realistic, Octane Render, Unreal engine`; the
+negative prompt is one space. The source is scaled with area interpolation to a
+maximum dimension of 1536. The optional 4-step LoRA remains bypassed; enabling
+it requires changing the sampler settings appropriately.
+
+The two native **Load Image** nodes are intentionally separate. **Image To
+Mask** reads the red channel of the mask PNG. That source `inpaint_mask` defines
+the region supplied to the inpainting ControlNet and the latent noise mask. It
+is not the Advanced-ControlNet effect mask. `effect_mask_optional` is left
+unconnected and independently limits where control is injected. The Apply node
+also exposes unconnected timestep keyframe, latent keyframe, and weights ports
+for focused reviewer experiments.
+
+## Measured validation evidence
+
+These results were measured with fixed inputs and settings; they are recorded
+here rather than inferred from the example image:
+
+- A fresh isolated vanilla-versus-Advanced run had latent maximum/mean absolute
+  differences `0/0`, pixel maximum/mean differences `0/0`, and 0 changed
+  pixels.
+- An all-one effect mask exactly equaled unmasked Advanced output at latent and
+  pixel level. An all-zero effect mask exactly equaled no ControlNet at latent
+  and pixel level.
+- For right-half token-mask injection, relative to full control the left latent
+  mean delta was `0` and the right was `0.1332103`; relative to no control the
+  left was `0` and the right was `0.1835042`.
+- In a per-latent batch, the sample with strength 0 exactly equaled no control
+  at latent and pixel level.
+- Soft weights, timestep scheduling, and two-control stacking each executed
+  successfully.
+- The existing Anima real workflow rerun retained exact before/after latent and
+  pixel equality.
+
+Frontend and API validation for a missing source mask names `inpaint_mask`.
+Supplying an incompatible model produces this exact error:
+`The provided ControlNet does not use an inpaint source mask; use Apply Advanced
+ControlNet instead.`
+
+Workflow and result screenshots are linked from the PR instead of stored here
+to avoid repository growth.