blosc2.open cannot open files containing Chinese characters.

When using blosc2.open to open a file containing Chinese characters, an error occurs
- OS: Windows 10
- blosc2.__version__ '3.10.0'

blosc2.open('E:\\456\\测试array.b2')
Traceback (most recent call last):
File "D:\Tools\jetbrains\PyCharm 2025.2.0.1\plugins\python-ce\helpers\pydev\pydevconsole.py", line 364, in runcode
coro = func()
^^^^^^
File "", line 1, in
File "C:\Projects\test\.venv\Lib\site-packages\blosc2\schunk.py", line 1593, in open
res = blosc2_ext.open(urlpath, mode, offset, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "blosc2/blosc2_ext.pyx", line 2015, in blosc2.blosc2_ext.open
raise RuntimeError(f'blosc2_schunk_open_offset({urlpath!r}, {offset!r}) returned NULL')
RuntimeError: blosc2_schunk_open_offset('E:\\456\\测试array.b2', 0) returned NULL

Reproduce the failure on Windows 10 with blosc2.open and the reported Chinese-character path. Start at schunk.py:1593 and blosc2_ext.pyx:2015, then trace the open entry point to determine where the path is rejected; done means that this path opens successfully without the reported RuntimeError.

Written by the indexing model from the issue text.