feat(asl): Add DeepSearch smart literature retrieval MVP

Features:
- Integrate unifuncs DeepSearch API (OpenAI compatible protocol)
- SSE real-time streaming for AI thinking process display
- Natural language input, auto-generate PubMed search strategy
- Extract and display PubMed literature links
- Database storage for task records (asl_research_tasks)

Backend:
- researchService.ts - Core business logic with SSE streaming
- researchController.ts - SSE stream endpoint
- researchWorker.ts - Async task worker (backup mode)
- schema.prisma - AslResearchTask model

Frontend:
- ResearchSearch.tsx - Search page with unified content stream
- ResearchSearch.css - Styling (unifuncs-inspired simple design)
- ASLLayout.tsx - Enable menu item
- api/index.ts - Add research API functions

API Endpoints:
- POST /api/v1/asl/research/stream - SSE streaming search
- POST /api/v1/asl/research/tasks - Async task creation
- GET /api/v1/asl/research/tasks/:taskId/status - Task status

Documentation:
- Development record for DeepSearch integration
- Update ASL module status (v1.5)
- Update system status (v3.7)

Known limitations:
- SSE mode, task interrupts when leaving page
- Cost ~0.3 RMB per search (unifuncs API)

backend/src/modules/asl/controllers/researchController.ts

@@ -0,0 +1,137 @@
+/**
+ * 智能文献检索 Controller
+ * 
+ * SSE 流式 + PubMed 链接提取
+ */
+
+import { FastifyRequest, FastifyReply } from 'fastify';
+import { researchService } from '../services/researchService.js';
+import { logger } from '../../../common/logging/index.js';
+
+interface SearchBody {
+  projectId: string;
+  query: string;
+}
+
+/**
+ * POST /api/v1/asl/research/stream
+ * SSE 实时流式检索
+ */
+export async function streamSearch(
+  request: FastifyRequest<{ Body: SearchBody }>,
+  reply: FastifyReply
+) {
+  const { projectId, query } = request.body;
+  const userId = request.user?.userId;
+
+  if (!userId) {
+    return reply.code(401).send({ success: false, error: '用户未认证' });
+  }
+
+  if (!query?.trim()) {
+    return reply.code(400).send({ success: false, error: '请输入检索问题' });
+  }
+
+  logger.info('[ResearchController] Starting SSE stream', { userId, queryLength: query.length });
+
+  // 设置 SSE 响应头
+  reply.raw.writeHead(200, {
+    'Content-Type': 'text/event-stream',
+    'Cache-Control': 'no-cache',
+    'Connection': 'keep-alive',
+    'Access-Control-Allow-Origin': '*',
+  });
+
+  try {
+    const task = await researchService.createTaskRecord(projectId, userId, query);
+
+    reply.raw.write(`data: ${JSON.stringify({ type: 'task_created', taskId: task.id })}\n\n`);
+
+    await researchService.executeStreamSearch(
+      task.id,
+      query,
+      // 思考过程（统一追加）
+      (reasoning: string) => {
+        reply.raw.write(`data: ${JSON.stringify({ type: 'reasoning', content: reasoning })}\n\n`);
+      },
+      // 结果内容（统一追加）
+      (content: string) => {
+        reply.raw.write(`data: ${JSON.stringify({ type: 'content', content })}\n\n`);
+      },
+      // 完成（返回链接列表）
+      (result: { links: string[] }) => {
+        reply.raw.write(`data: ${JSON.stringify({ type: 'completed', links: result.links })}\n\n`);
+        reply.raw.end();
+      },
+      // 错误
+      (error: string) => {
+        reply.raw.write(`data: ${JSON.stringify({ type: 'error', error })}\n\n`);
+        reply.raw.end();
+      }
+    );
+  } catch (error: any) {
+    logger.error('[ResearchController] Stream search failed', { error: error.message });
+    reply.raw.write(`data: ${JSON.stringify({ type: 'error', error: error.message })}\n\n`);
+    reply.raw.end();
+  }
+}
+
+/**
+ * POST /api/v1/asl/research/tasks
+ * 创建检索任务（异步模式）
+ */
+export async function createTask(
+  request: FastifyRequest<{ Body: SearchBody }>,
+  reply: FastifyReply
+) {
+  try {
+    const { projectId, query } = request.body;
+    const userId = request.user?.userId;
+
+    if (!userId) {
+      return reply.code(401).send({ success: false, error: '用户未认证' });
+    }
+
+    if (!projectId) {
+      return reply.code(400).send({ success: false, error: '缺少 projectId' });
+    }
+
+    if (!query?.trim()) {
+      return reply.code(400).send({ success: false, error: '请输入检索问题' });
+    }
+
+    const task = await researchService.createTask({ projectId, userId, query: query.trim() });
+    return reply.send({ success: true, data: task });
+  } catch (error: any) {
+    logger.error('[ResearchController] Create task failed', { error: error.message });
+    return reply.code(500).send({ success: false, error: error.message });
+  }
+}
+
+/**
+ * GET /api/v1/asl/research/tasks/:taskId/status
+ * 获取任务状态
+ */
+export async function getTaskStatus(
+  request: FastifyRequest<{ Params: { taskId: string } }>,
+  reply: FastifyReply
+) {
+  try {
+    const { taskId } = request.params;
+
+    if (!taskId) {
+      return reply.code(400).send({ success: false, error: '缺少 taskId' });
+    }
+
+    const status = await researchService.getTaskStatus(taskId);
+
+    if (!status) {
+      return reply.code(404).send({ success: false, error: '任务不存在' });
+    }
+
+    return reply.send({ success: true, data: status });
+  } catch (error: any) {
+    logger.error('[ResearchController] Get task status failed', { error: error.message });
+    return reply.code(500).send({ success: false, error: error.message });
+  }
+}