stalign on Windows: `ENOENT ... mimetype`, `SuppressedError`, and a 404 downloading whisper-cpp-windows-x64-cuda

Running the native Windows build of stalign, the markup step fails with [Error: ENOENT: no such file or directory, open 'C:\Users\...\Temp\storyteller-platform-epub-<uuid>.epub\mimetype'], and the align step dies immediately with SuppressedError: An error was suppressed during disposal and no other output even at --log-level debug. Later versions instead fail transcription with Error: Failed to download: 404 Not Found for a whisper-cpp Windows CUDA archive.

Resolution: These are three separate Windows-specific bugs, fixed and worked around in stages. The mimetype ENOENT was a bug in extracting the EPUB archive to the temp dir and is fixed in stalign 0.1.47; the opaque SuppressedError in the align step was fixed in 0.1.55, which surfaces the real error instead. The 404 is not a bug in your setup: stalign detects CUDA via nvidia-smi and defaults to variant cuda-13.1.0, but no Windows CUDA build of whisper.cpp is published (the CI runner cannot build it in reasonable time), so the package URL genuinely does not exist. Force the CPU build by setting the environment variable STORYTELLER_WHISPER_VARIANT=windows-x64-cpu before running — the --cpu-override cpu flag does not do this. Even then, native Windows alignment is not fully usable: the align step writes unstripped Windows paths into the media overlays (src="../Audio/intermediate\<book>\processed_audio\00001-00001.mp4" instead of src="../Audio/00001-00001.mp4"), producing a broken EPUB. Until that is fixed, run transcription and alignment through Docker or WSL, which works correctly.