fix: TaskManager accepts max_workers argument in __new__

- Updated TaskManager.__new__ to accept max_workers parameter
- Fixed get_task_manager to return TaskManager._instance directly
- This fixes the initialization error: 'TaskManager.new() got an unexpected keyword argument'

core/tasks.py

@@ -78,12 +78,13 @@ class TaskManager:
     _instance = None
     _lock = threading.Lock()
     
-    def __new__(cls):
+    def __new__(cls, max_workers: int = 4):
         if cls._instance is None:
             with cls._lock:
                 if cls._instance is None:
                     cls._instance = super().__new__(cls)
                     cls._instance._initialized = False
+                    cls._instance._max_workers = max_workers
         return cls._instance
     
     def __init__(self, max_workers: int = 4):
@@ -354,4 +355,4 @@ def get_task_manager(max_workers: int = 4) -> TaskManager:
     # Create with specified max_workers if not already created
     if TaskManager._instance is None:
         TaskManager(max_workers=max_workers)
-    return TaskManager()
+    return TaskManager._instance