Uploading .astro files throws a "not supported" error.

Provider: Self-hosted New API, endpoint v1/chat/completions, model gemini-3-pro-preview-bs.

Requires uploading .astro files, but throws a generation error: AI_UnsupportedFunctionalityError: 'file part media type application/octet-stream' functionality not supported.

My hypothesis is that if the uploaded file's extension doesn't match any recognized MIME types, it defaults to treating it as `text/plain`.