asyncio.create_subprocess_exec cannot run .cmd/.bat files on Windows
because CreateProcess expects a valid PE executable. npm-installed LSP
servers (intelephense, typescript-language-server, etc.) ship as .cmd
shims on Windows, causing WinError 193 on spawn.
Detect .cmd/.bat extensions and wrap with cmd.exe /c before spawning.
Gated behind sys.platform == 'win32' — no code path changes elsewhere.
Fixes#34864