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/package-lock.json

@@ -30,6 +30,7 @@
         "jsonrepair": "^3.13.1",
         "jsonwebtoken": "^9.0.2",
         "jspdf": "^3.0.3",
+        "openai": "^6.16.0",
         "p-queue": "^9.0.1",
         "pg-boss": "^12.5.2",
         "prisma": "^6.17.0",
@@ -3790,6 +3791,27 @@
         "fn.name": "1.x.x"
       }
     },
+    "node_modules/openai": {
+      "version": "6.16.0",
+      "resolved": "https://registry.npmmirror.com/openai/-/openai-6.16.0.tgz",
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+      "license": "Apache-2.0",
+      "bin": {
+        "openai": "bin/cli"
+      },
+      "peerDependencies": {
+        "ws": "^8.18.0",
+        "zod": "^3.25 || ^4.0"
+      },
+      "peerDependenciesMeta": {
+        "ws": {
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+        },
+        "zod": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/p-queue": {
       "version": "9.0.1",
       "resolved": "https://registry.npmmirror.com/p-queue/-/p-queue-9.0.1.tgz",