refactor : 并行启动 Strategy 模式重构，local_rank 解耦

- setup_parallel 接收 local_rank 参数，不再读环境变量推导
- TorchrunStrategy 从 env 读取 LOCAL_RANK，LocalStrategy 用 rank
- _detect_launcher() 分级检测替代内联 RANK 检查
- _run_single_rank 统一入口，消除 _run_single/_run_multi 重复
- 优雅退出：except BaseException 终止子进程并 re-join
- gradient_checkpointing_modules 判定提取到外部变量

scripts/tools/train.py

@@ -315,6 +315,8 @@ def train(
         },
     )
 
+    grad_ckpt_modules = [DecoderBlock] if gradient_checkpointing else []
+
     train_config = TrainConfig(
         model_fn=model_fn,
         strategy=train_type,
@@ -332,9 +334,6 @@ def train(
         random_seed=random_seed,
         num_workers=num_workers,
         pin_memory=pin_memory,
-        gradient_checkpointing_modules=[DecoderBlock]
-        if gradient_checkpointing
-        else [],
         nprocs=nprocs,
         backend=backend,
         master_addr=master_addr,
@@ -342,6 +341,7 @@ def train(
         parallel_mode=parallel_mode,
         device_type=device_type,
         start_method=start_method,
+        gradient_checkpointing_modules=grad_ckpt_modules,
         executor_kwargs=executor_kwargs,
         extra_kwargs=strategy_kwargs,
     )