UvAPI hardcodes POSIX venv paths and fails on Windows (bin/python vs Scripts/python.exe)

[yoodn]

clearml_agent/helper/package/uv_api.py hardcodes POSIX virtualenv paths in several places:

• .venv/bin/python in UvAPI.get_python_command()
• /bin/python... after uv venv creation
• <uv_install_venv>/bin/uv in install_uv_package()

On Windows, venv executables are located under Scripts/, e.g. Scripts/python.exe and Scripts/uv.exe.
The existing VirtualenvPip implementation already uses select_for_platform(linux="bin/python", windows="scripts/python.exe"), so UvAPI should probably use the same platform-specific logic.