fix: disable reference images for grok2 provider (edit API not yet supported)

src/lib/model-gateway/openai-compat/image.ts

@@ -154,7 +154,11 @@ export async function generateImageViaOpenAICompat(request: OpenAICompatImageReq
   const rawSize = resolveRawSize(options)
   const size = normalizeOpenAIImageSize(rawSize)
 
-  if (referenceImages.length > 0) {
+  // Grok2 暂不支持图片编辑接口，忽略参考图
+  const providerKey = providerId.split('-')[0]
+  const shouldUseReferenceImages = referenceImages.length > 0 && providerKey !== 'grok2'
+
+  if (shouldUseReferenceImages) {
     const response = await client.images.edit({
       model: normalizedModelId,
       prompt,