fix(web): 修正在线测试模型类型筛选

移除可能将 image_to_video 误判为图像模型的子串回退，在没有匹配模型时显示空状态。

新增图像生成、图像编辑和视频模式回归测试。验证通过：前端 94 项测试、类型检查、lint 和生产构建。

apps/web/src/pages/PlaygroundPage.models.test.ts

@@ -0,0 +1,48 @@
+import type { PlatformModel } from '@easyai-ai-gateway/contracts';
+import { describe, expect, it } from 'vitest';
+import { filterModelsForMode } from './PlaygroundPage';
+
+function model(id: string, modelType: string[]) {
+  return { id, modelType } as PlatformModel;
+}
+
+function modelIds(models: PlatformModel[]) {
+  return models.map((item) => item.id);
+}
+
+describe('playground model filtering', () => {
+  const models = [
+    model('image-generation', ['image_generate']),
+    model('legacy-image', ['image']),
+    model('image-edit', ['image_edit']),
+    model('image-to-video', ['video_generate', 'image_to_video']),
+    model('text-to-video', ['text_to_video']),
+  ];
+
+  it('only shows image generation models when no reference image is present', () => {
+    expect(modelIds(filterModelsForMode(models, 'image', false, 'text_to_video'))).toEqual([
+      'image-generation',
+      'legacy-image',
+    ]);
+  });
+
+  it('only shows image editing models when a reference image is present', () => {
+    expect(modelIds(filterModelsForMode(models, 'image', true, 'text_to_video'))).toEqual([
+      'legacy-image',
+      'image-edit',
+    ]);
+  });
+
+  it('does not fall back to image-to-video models when no image model is available', () => {
+    const videoOnlyModels = [
+      model('kling-3-turbo', ['video_generate', 'image_to_video']),
+      model('kling-1-5', ['image_to_video']),
+    ];
+
+    expect(filterModelsForMode(videoOnlyModels, 'image', false, 'text_to_video')).toEqual([]);
+  });
+
+  it('keeps image-to-video models available for the matching video mode', () => {
+    expect(modelIds(filterModelsForMode(models, 'video', false, 'first_last_frame'))).toContain('image-to-video');
+  });
+});

apps/web/src/pages/PlaygroundPage.tsx

@@ -810,7 +810,7 @@ function Composer(props: {
         <Select className="playgroundModelSelect" value={props.selectedModel ?? ''} disabled={!props.modelOptions.length} onChange={(event) => props.onModelChange(event.target.value)}>
           {props.modelOptions.length ? props.modelOptions.map((item) => (
             <option value={item.value} key={item.value}>{modelOptionLabel(item)}</option>
-          )) : <option value="">模型选择</option>}
+          )) : <option value="">{props.compact ? '模型选择' : '暂无可用模型'}</option>}
         </Select>
         {props.mode !== 'chat' && props.mediaSettings && props.onMediaSettingsChange && (
           <MediaSettingsPopover
@@ -977,25 +977,25 @@ function mediaPromptPlaceholder(mode: PlaygroundMode) {
   return placeholderByMode.chat;
 }
 
-function filterModelsForMode(models: PlatformModel[], mode: PlaygroundMode, hasReference: boolean, videoMode: VideoCreateMode) {
+export function filterModelsForMode(models: PlatformModel[], mode: PlaygroundMode, hasReference: boolean, videoMode: VideoCreateMode) {
   if (mode === 'chat') {
-    return filterWithFallback(models, ['text_generate', 'chat', 'responses', 'text']);
+    return filterModelsByType(models, ['text_generate', 'chat', 'responses', 'text']);
   }
   if (mode === 'image') {
     const preferredTypes = hasReference ? ['image_edit', 'images.edits'] : ['image_generate', 'images.generations'];
-    return filterWithFallback(models, [...preferredTypes, 'image']);
+    return filterModelsByType(models, [...preferredTypes, 'image']);
   }
   const videoTypesByMode: Record<VideoCreateMode, string[]> = {
     first_last_frame: ['video_first_last_frame', 'image_to_video', 'video_generate'],
     omni_reference: ['omni_video', 'video_reference', 'video_generate'],
     text_to_video: ['text_to_video', 'video_generate'],
   };
-  return filterWithFallback(models, [...videoTypesByMode[videoMode], 'video']);
+  return filterModelsByType(models, [...videoTypesByMode[videoMode], 'video']);
 }
 
-function filterWithFallback(models: PlatformModel[], modelTypes: string[]) {
-  const exact = models.filter((model) => model.modelType.some((type) => modelTypes.includes(type)));
-  return exact.length ? exact : models.filter((model) => modelTypes.some((type) => model.modelType.some((modelType) => modelType.includes(type) || type.includes(modelType))));
+function filterModelsByType(models: PlatformModel[], modelTypes: string[]) {
+  const acceptedTypes = new Set(modelTypes);
+  return models.filter((model) => model.modelType.some((type) => acceptedTypes.has(type)));
 }
 
 function buildModelOptions(models: PlatformModel[]): ModelOption[] {