refactor(executors): 移除私有函数前缀并修正导入

src/pyflowx/executors.py

@@ -53,7 +53,7 @@ class Strategy(enum.Enum):
     ASYNC = "async"
 
 
-def _normalize_strategy(strategy: str | Strategy) -> Strategy:
+def normalize_strategy(strategy: str | Strategy) -> Strategy:
     """将字符串或 Strategy 归一化为 Strategy 枚举.
 
     Parameters
@@ -436,7 +436,7 @@ def run(
         任何任务耗尽重试后仍失败时。运行在失败层中止；后续层的任务
         不会被执行。
     """
-    normalized = _normalize_strategy(strategy)
+    normalized = normalize_strategy(strategy)
 
     graph.validate()
     layers = graph.layers()

src/pyflowx/runner.py

@@ -26,7 +26,7 @@ import sys
 from typing import Sequence
 
 from .errors import PyFlowXError
-from .executors import Strategy, _normalize_strategy, run
+from .executors import Strategy, normalize_strategy, run
 from .graph import Graph
 
 __all__ = ["CliExitCode", "CliRunner"]
@@ -132,7 +132,7 @@ class CliRunner:
                     f"CliRunner 命令 {name!r} 的值必须是 Graph 实例, 实际是 {type(graph).__name__}"
                 )
         self._graphs: dict[str, Graph] = dict(graphs)
-        self._strategy: Strategy = _normalize_strategy(strategy)
+        self._strategy: Strategy = normalize_strategy(strategy)
         self._description: str = description
         self._verbose: bool = verbose