fix: resolve ruff linter errors in multi_dtype_passes

- Add explicit re-export in __init__.py for DtypeConversionPass
- Use TYPE_CHECKING for forward reference in pass_mgr.py
- Remove unused torch import in autocast_wrapper_pass.py
- Fix type annotation to use type[DtypeConversionPass]

Author: Dayuxiaoshui

graph_net/torch/multi_dtype_passes/__init__.py

@@ -1 +1,3 @@
-from graph_net.torch.multi_dtype_passes.pass_base import DtypeConversionPass
+from graph_net.torch.multi_dtype_passes.pass_base import (
+    DtypeConversionPass as DtypeConversionPass,
+)

graph_net/torch/multi_dtype_passes/autocast_wrapper_pass.py

@@ -5,8 +5,8 @@
 to handle operators that don't support low-precision computation natively.
 """
 
-import torch
 import torch.fx as fx
+
 from graph_net.torch.multi_dtype_passes.pass_base import DtypeConversionPass
 
 

graph_net/torch/multi_dtype_passes/pass_mgr.py

@@ -2,11 +2,18 @@
 Pass manager for dtype conversion passes.
 """
 
-from graph_net.imp_util import load_module
+from __future__ import annotations
+
 import os
+from typing import TYPE_CHECKING
+
+from graph_net.imp_util import load_module
+
+if TYPE_CHECKING:
+    from graph_net.torch.multi_dtype_passes.pass_base import DtypeConversionPass
 
 
-def get_dtype_conversion_pass(pass_name: str) -> "DtypeConversionPass":
+def get_dtype_conversion_pass(pass_name: str) -> type[DtypeConversionPass]:
     """
     Load a dtype conversion pass by name.