feat: AI测试输出渲染Markdown/流式响应、Coze/Dify适配器优化

- 新增 MarkdownPreview 组件，支持 AI 测试输出 Markdown 渲染
- Coze 适配器优化：支持流式响应、工作流接口调用、SSE事件处理
- Dify 适配器优化：支持停止接口、流式聊天、SSE事件解析
- web-admin 添加 markdown-it 和 highlight.js 依赖
- AI 配置列表页面优化测试对话框输出显示

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web-admin/src/api/aiconfig.ts

@@ -296,6 +296,36 @@ function parseSseFrame(frame: string): AiRuntimeStreamEvent | null {
   }
 }
 
+export function normalizeAiText(value?: string): string {
+  if (!value) return ''
+  const trimmed = value.trim()
+  if (!trimmed.startsWith('{') || !trimmed.endsWith('}')) return value
+  try {
+    const parsed = JSON.parse(trimmed)
+    const extracted = extractTextValue(parsed)
+    return extracted ? normalizeAiText(extracted) : value
+  } catch {
+    return value
+  }
+}
+
+function extractTextValue(value: any): string {
+  if (!value || typeof value !== 'object' || Array.isArray(value)) return ''
+  for (const key of ['output', 'answer', 'content', 'text', 'result']) {
+    const item = value[key]
+    if (typeof item === 'string' && item.trim()) return item
+    if (item && typeof item === 'object' && !Array.isArray(item)) {
+      const nested = extractTextValue(item)
+      if (nested) return nested
+    }
+  }
+  for (const key of ['data', 'outputs', 'message']) {
+    const nested = extractTextValue(value[key])
+    if (nested) return nested
+  }
+  return ''
+}
+
 async function fetchSseStream(
   url: string,
   body: Record<string, any>,
@@ -327,7 +357,7 @@ async function fetchSseStream(
       const event = parseSseFrame(frame)
       if (!event) return
       if (event.type === 'delta') {
-        output += event.content || ''
+        output += normalizeAiText(event.content || '')
       }
       onEvent(event, output)
       if (event.type === 'error') {