feat(lpt-ai)：新增 /fetch-title 网页标题抓取接口

POST /fetch-title { url } → { url, title }
- 服务端 fetch 目标页面，正则提取 <title> 标签
- 10 秒超时，抓取失败时返回 title: null
- 请求日志记录到 logStore

src/routes/ai.ts

@@ -5,6 +5,7 @@
 import type { FastifyInstance } from "fastify";
 import { isAvailable, loadConfig } from "../llm/client.js";
 import { createTask, getTask, type TaskType } from "../task-queue.js";
+import { logStore } from "../admin/store.js";
 
 export async function aiRoutes(app: FastifyInstance): Promise<void> {
   const config = loadConfig();
@@ -39,4 +40,48 @@ export async function aiRoutes(app: FastifyInstance): Promise<void> {
     }
     return task;
   });
+
+  /** 抓取网页标题 */
+  app.post<{ Body: { url: string } }>("/fetch-title", async (request, reply) => {
+    const { url } = request.body ?? {};
+    const t0 = Date.now();
+
+    if (!url || typeof url !== "string" || (!url.startsWith("http://") && !url.startsWith("https://"))) {
+      return reply.status(400).send({ error: "无效的 URL" });
+    }
+
+    try {
+      const controller = new AbortController();
+      const timer = setTimeout(() => controller.abort(), 10_000);
+      const response = await fetch(url, { signal: controller.signal });
+      clearTimeout(timer);
+
+      const html = await response.text();
+      const match = html.match(/<title[^>]*>([^<]+)<\/title>/i);
+      const title = match ? match[1].trim() : null;
+
+      logStore.add({
+        timestamp: new Date().toISOString(),
+        endpoint: "/fetch-title",
+        model: "",
+        durationMs: Date.now() - t0,
+        status: 200,
+        requestBody: { url },
+        responseBody: { url, title },
+      });
+      return { url, title };
+    } catch (err) {
+      logStore.add({
+        timestamp: new Date().toISOString(),
+        endpoint: "/fetch-title",
+        model: "",
+        durationMs: Date.now() - t0,
+        status: 502,
+        requestBody: { url },
+        responseBody: { url, title: null },
+        error: err instanceof Error ? err.message : String(err),
+      });
+      return { url, title: null };
+    }
+  });
 }