[Model] Add JoyAI-Image-Edit pipeline support (#4112)

Signed-off-by: nagisa-kun <1434936049@qq.com>
Signed-off-by: nagisa <1434936049@qq.com>
Signed-off-by: hurukawa <61525444+nagisa-kunhah@users.noreply.github.com>

docs/user_guide/examples/online_serving/image_to_image.md

@@ -3,10 +3,14 @@
 Source <https://github.com/vllm-project/vllm-omni/tree/main/examples/online_serving/image_to_image>.
 
 
-This example demonstrates how to deploy Qwen-Image-Edit model for online image editing service using vLLM-Omni.
+This example demonstrates how to deploy image-to-image models for online image editing service using vLLM-Omni.
+
+Supported models include Qwen-Image-Edit, BAGEL, JoyAI-Image-Edit, and other image-to-image pipelines.
 
 For **multi-image** input editing, use **Qwen-Image-Edit-2509** (QwenImageEditPlusPipeline) and send multiple images in the user message content.
 
+For **JoyAI-Image-Edit**, use `jdopensource/JoyAI-Image-Edit-Diffusers` and send exactly one input image.
+
 ## Start Server
 
 ### Basic Start
@@ -24,6 +28,12 @@ vllm serve Qwen/Qwen-Image-Edit --omni --port 8092
 vllm serve Qwen/Qwen-Image-Edit-2509 --omni --port 8092
 ```
 
+### JoyAI-Image-Edit
+
+```bash
+vllm serve jdopensource/JoyAI-Image-Edit-Diffusers --omni --port 8092
+```
+
 ### Start with Parameters
 
 
@@ -76,6 +86,11 @@ curl -s http://localhost:8092/v1/chat/completions \
   | cut -d',' -f2 | base64 -d > output.png
 ```
 
+For JoyAI-Image-Edit, set classifier-free guidance with `guidance_scale`
+in `extra_body` (default: `4.0`). `true_cfg_scale` remains supported as an
+alias; if both are provided, their values must match. Values at or below `1.0`
+disable CFG.
+
 ### Method 2: Using OpenAI Python SDK
 
 ```python