add new open ai image model

Signed-off-by: jonghoon park <dev@jonghoonpark.com>

Author: dev-jonghoonpark

models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiImageApi.java

@@ -91,6 +91,11 @@ public static Builder builder() {
 	 */
 	public enum ImageModel {
 
+		/**
+		 * The state-of-the-art image generation model released in April 2025.
+		 */
+		GPT_IMAGE_1("gpt-image-1"),
+
 		/**
 		 * The latest DALL·E model released in Nov 2023.
 		 */

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/image/openai-image.adoc

@@ -1,7 +1,7 @@
 = OpenAI Image Generation
 
 
-Spring AI supports DALL-E, the Image generation model from OpenAI.
+Spring AI supports Image generation models (DALL-E, GPT Image 1) from OpenAI.
 
 == Prerequisites
 
@@ -108,8 +108,8 @@ The prefix `spring.ai.openai.image` is the property prefix that lets you configu
 | spring.ai.openai.image.options.n            | The number of images to generate. Must be between 1 and 10. For dall-e-3, only n=1 is supported.  | -
 | spring.ai.openai.image.options.model        | The model to use for image generation.  | OpenAiImageApi.DEFAULT_IMAGE_MODEL
 | spring.ai.openai.image.options.quality      | The quality of the image that will be generated. HD creates images with finer details and greater consistency across the image. This parameter is only supported for dall-e-3. | -
-| spring.ai.openai.image.options.response_format | The format in which the generated images are returned. Must be one of URL or b64_json. | -
-| `spring.ai.openai.image.options.size`       | The size of the generated images. Must be one of 256x256, 512x512, or 1024x1024 for dall-e-2. Must be one of 1024x1024, 1792x1024, or 1024x1792 for dall-e-3 models. | -
+| `spring.ai.openai.image.options.response_format` | The format in which the generated images are returned. Must be one of URL or b64_json. This parameter isn't supported for gpt-image-1 which will always return base64-encoded images. | -
+| `spring.ai.openai.image.options.size`       | The size of the generated images. Must be one of 256x256, 512x512, or 1024x1024 for dall-e-2. Must be one of 1024x1024, 1792x1024, or 1024x1792 for dall-e-3. Must be one of 1024x1024, 1536x1024 (landscape), 1024x1536 (portrait), or auto (default value) for gpt-image-1 | -
 | `spring.ai.openai.image.options.size_width` | The width of the generated images. Must be one of 256, 512, or 1024 for dall-e-2.  | -
 | `spring.ai.openai.image.options.size_height`| The height of the generated images. Must be one of 256, 512, or 1024 for dall-e-2. | -
 | `spring.ai.openai.image.options.style`      | The style of the generated images. Must be one of vivid or natural. Vivid causes the model to lean towards generating hyper-real and dramatic images. Natural causes the model to produce more natural, less hyper-real looking images. This parameter is only supported for dall-e-3. | -