perf: waiting_queue 改用 deque，pull_candidates 从 O(n²) 降到 O(1)

- list.pop(0) 每次左移全部元素，改 deque.popleft() 指针操作
- return_to_waiting 从 slice 整体复制改 appendleft 逐个插入
- 热路径 refill 阶段不再卡顿

astrai/inference/core/task.py

@@ -2,8 +2,9 @@ import logging
 import threading
 import time
 import uuid
+from collections import deque
 from enum import Enum
-from typing import Any, Callable, Dict, List, Optional
+from typing import Any, Callable, Deque, Dict, List, Optional
 
 from astrai.tokenize.tokenizer import AutoTokenizer
 
@@ -76,7 +77,7 @@ class TaskManager:
         self.max_seq_len = max_seq_len
         self.max_prompt_len = max_prompt_len
 
-        self.waiting_queue: List[Task] = []
+        self.waiting_queue: Deque[Task] = deque()
         self.active_tasks: List[Task] = []
 
         self._task_event = threading.Event()
@@ -129,7 +130,9 @@ class TaskManager:
     def remove_task(self, task_id: str) -> List[Task]:
         with self._lock:
             removed_active = [t for t in self.active_tasks if t.task_id == task_id]
-            self.waiting_queue = [t for t in self.waiting_queue if t.task_id != task_id]
+            self.waiting_queue = deque(
+                t for t in self.waiting_queue if t.task_id != task_id
+            )
             self.active_tasks = [t for t in self.active_tasks if t.task_id != task_id]
         return removed_active
 
@@ -166,7 +169,7 @@ class TaskManager:
         with self._lock:
             take = min(n, len(self.waiting_queue))
             for _ in range(take):
-                to_add.append(self.waiting_queue.pop(0))
+                to_add.append(self.waiting_queue.popleft())
         return to_add
 
     def activate(self, task: Task) -> None:
@@ -176,7 +179,8 @@ class TaskManager:
 
     def return_to_waiting(self, tasks: List[Task]) -> None:
         with self._lock:
-            self.waiting_queue[:0] = tasks
+            for task in reversed(tasks):
+                self.waiting_queue.appendleft(task)
 
     def has_work(self) -> bool:
         return bool(self.active_tasks or self.waiting_queue)