feat: 新增任务状态管理和API支持

- 添加任务状态API路由，支持获取当前用户的任务状态和待处理任务列表
- 实现任务追踪服务，使用Redis存储任务状态
- 更新回忆录处理逻辑，集成Celery任务提交和状态更新
- 增强测试用例，支持任务状态的获取和清除功能
- 优化代码结构，提升可读性和维护性

api/agents/memoir_processor.py

@@ -146,6 +146,30 @@ class BackgroundTaskRunner:
         self.analyzer = ContentAnalyzer()
         self.generator = MemoirGenerator()
 
+    async def _submit_task(self, user_id: str, segment_ids: List[str]) -> str | None:
+        """
+        提交 Celery 任务并记录
+        
+        Returns:
+            任务 ID，失败返回 None
+        """
+        try:
+            from tasks.memoir_tasks import process_memoir_segments
+            from services.task_tracker import task_tracker
+            
+            # 提交到 Celery
+            result = process_memoir_segments.delay(user_id, segment_ids)
+            task_id = result.id
+            
+            # 记录任务
+            await task_tracker.add_task(user_id, task_id, "memoir")
+            
+            logger.info(f"已提交 Celery 任务: user_id={user_id}, task_id={task_id}, segments={len(segment_ids)}")
+            return task_id
+        except Exception as e:
+            logger.error(f"提交 Celery 任务失败: {e}")
+            return None
+
     async def queue_message(self, user_id: str, segment_id: str) -> None:
         """
         将消息加入处理队列
@@ -167,20 +191,20 @@ class BackgroundTaskRunner:
                 await asyncio.sleep(self.debounce_seconds)
                 segment_ids = self._pending.pop(user_id, [])
                 if segment_ids:
-                    # 提交到 Celery
-                    from tasks.memoir_tasks import process_memoir_segments
-                    process_memoir_segments.delay(user_id, segment_ids)
-                    logger.info(f"已提交 Celery 任务: user_id={user_id}, segments={len(segment_ids)}")
+                    await self._submit_task(user_id, segment_ids)
             except asyncio.CancelledError:
                 pass
             except Exception as e:
-                logger.error(f"提交 Celery 任务失败: {e}")
+                logger.error(f"延迟提交任务失败: {e}")
         
         self._timers[user_id] = asyncio.create_task(delayed_submit())
 
-    async def flush_pending(self, user_id: str) -> None:
+    async def flush_pending(self, user_id: str) -> str | None:
         """
         立即提交用户的待处理任务（用于对话结束时）
+        
+        Returns:
+            任务 ID，无任务或失败返回 None
         """
         # 取消定时器
         if user_id in self._timers:
@@ -190,6 +214,5 @@ class BackgroundTaskRunner:
         # 提交待处理任务
         segment_ids = self._pending.pop(user_id, [])
         if segment_ids:
-            from tasks.memoir_tasks import process_memoir_segments
-            process_memoir_segments.delay(user_id, segment_ids)
-            logger.info(f"立即提交 Celery 任务: user_id={user_id}, segments={len(segment_ids)}")
+            return await self._submit_task(user_id, segment_ids)
+        return None