feat: 添加知识库检索功能和改进模型路由错误处理

- 在ChatRequest中添加Citation事件类型，支持引用来源展示
- 实现聊天上下文准备服务，构建带源元数据的受限聊天上下文
- 添加ThreadedProcess类以支持Windows平台的子进程操作
- 改进检索引擎中的错误处理和向量搜索逻辑
- 实现严格的嵌入模型验证和索引重建机制
- 添加前端聊天界面的知识库检索开关
- 实现搜索历史记录功能和错误降级处理
- 更新模型路由设置提示信息以反映索引重建需求

backend/app/local_models/runtime.py

@@ -100,9 +100,16 @@ class Runtime:
             env = {**os.environ, "HF_HUB_OFFLINE": "1", "TRANSFORMERS_OFFLINE": "1",
                    "HF_HUB_DISABLE_TELEMETRY": "1", "OMP_NUM_THREADS": str(config.cpu_threads),
                    "PYTHONIOENCODING": "utf-8"}
-            process = await asyncio.create_subprocess_exec(str(interpreter()), str(Path(__file__).with_name("worker.py")),
-                stdin=asyncio.subprocess.PIPE, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.DEVNULL,
-                env=env, limit=16 * 1024 * 1024, **({"creationflags": 0x08000000} if os.name == "nt" else {}))
+            args = (str(interpreter()), str(Path(__file__).with_name("worker.py")))
+            options = {"env": env, "limit": 16 * 1024 * 1024,
+                       **({"creationflags": 0x08000000} if os.name == "nt" else {})}
+            try:
+                process = await asyncio.create_subprocess_exec(*args,
+                    stdin=asyncio.subprocess.PIPE, stdout=asyncio.subprocess.PIPE,
+                    stderr=asyncio.subprocess.DEVNULL, **options)
+            except NotImplementedError:
+                from app.local_models.process import ThreadedProcess
+                process = ThreadedProcess(args, **options)
             request = {"key": key, "operation": operation, "model_path": str(model_path(key).resolve()),
                        "config": config.model_dump(), "payload": payload}
             async def receive():
@@ -144,6 +151,8 @@ class Runtime:
             if process is not None and process.returncode is None:
                 process.kill()
                 await process.wait()
+            if process is not None and hasattr(process, "close"):
+                await process.close()
             self.active.pop(ticket, None)
             self.active_files.pop(ticket, None)
             if attempt: