Fix _resolve_path for local file URIs

Modify _resolve_path to use url_to_fs to extract the local path from file:// URIs before converting to Path. Added corresponding test cases.

TAG=agy

CONV=16c2f90a-014c-41d1-aced-31b0633c0464

Author: zhixiangli

src/lightning/fabric/utilities/cloud_io.py

@@ -188,7 +188,8 @@ def _resolve_path(path: _PATH) -> Union[str, Path]:
 
     """
     if _is_local_file_protocol(str(path)):
-        return Path(path)
+        _, urlpath = url_to_fs(str(path))
+        return Path(urlpath)
     return str(path)
 
 

tests/tests_fabric/utilities/test_cloud_io.py

@@ -165,6 +165,12 @@ def test_atomic_save_uses_write_for_local(tmp_path):
 def test_resolve_path_local_vs_remote(tmp_path):
     resolved = _resolve_path(str(tmp_path / "ckpt"))
     assert isinstance(resolved, Path)
+    assert resolved == tmp_path / "ckpt"
+
+    resolved_file_uri = _resolve_path("file:///tmp/test.txt")
+    assert isinstance(resolved_file_uri, Path)
+    assert resolved_file_uri == Path("/tmp/test.txt")
+
     resolved = _resolve_path("gs://bucket/checkpoints/epoch=1.ckpt")
     assert resolved == "gs://bucket/checkpoints/epoch=1.ckpt"
     assert isinstance(resolved, str)