fix(desktop): 修复搜索结果排版 — stripToolNarration 保留 markdown 结构

根因: stripToolNarration 按句子切分再用空格拼接，破坏了所有 markdown
格式（标题/列表/段落/代码块），导致搜索结果显示为纯文本墙。

修复: 改为按行处理，只过滤匹配叙述模式的行，保留 markdown 结构行
（标题/列表/空行/引用/代码/表格）。关键变化:
- 保留空行（markdown 段落分隔符）
- 保留以 #/-/*/数字/>/```/| 开头的结构行
- 仅过滤 LLM 内部叙述（"让我执行..."、"Let me..."等）

desktop/src/components/ChatArea.tsx

@@ -643,10 +643,14 @@ export function ChatArea({ compact, onOpenDetail }: { compact?: boolean; onOpenD
  * and Chinese ("让我执行...", "让我尝试..."). These are internal thoughts, not user-facing content.
  */
 function stripToolNarration(content: string): string {
-  const sentences = content.split(/(?<=[。！？.!?])\s*/);
+  // Process line-by-line to preserve markdown structure (headings, lists, paragraphs)
-  const filtered = sentences.filter(s => {
+  const lines = content.split('\n');
-    const t = s.trim();
+  const filtered = lines.filter(line => {
-    if (!t) return false;
+    const t = line.trim();
+    // Keep empty lines (paragraph breaks in markdown)
+    if (!t) return true;
+    // Keep markdown structural lines (headings, list items, horizontal rules, blockquotes, code)
+    if (/^(#{1,6}\s|[-*+]\s|\d+\.\s|>|\s*```|---|\|)/.test(t)) return true;
     // English narration patterns
     if (/^(?:Now )?[Ll]et me\s/i.test(t)) return false;
     if (/^I\s+(?:need to|keep getting|should|will try|have to|can try|must)\s/i.test(t)) return false;
@@ -656,8 +660,8 @@ function stripToolNarration(content: string): string {
     if (/^好的，让我为您/.test(t)) return false;
     return true;
   });
-  const result = filtered.join(' ').replace(/\s{2,}/g, ' ').trim();
+  const result = filtered.join('\n');
-  return result || content; // Fallback: if everything was stripped, show original
+  return result || content;
 }
 
 function MessageBubble({ message, onRetry }: { message: Message; setInput?: (text: string) => void; onRetry?: () => void }) {