Module adapters/drive

Adapter — Google Drive public file download.

Drive doesn't expose a clean anonymous download endpoint. What works in practice:

1. Hit drive.usercontent.google.com/download?id=...&confirm=t — this skips the virus-scan interstitial for most public files.
2. If the response is binary, we're done.
3. If the response is the HTML virus-scan interstitial (large files), parse the <form>, forward cookies, and retry with the hidden inputs as query params.