Upload files to Drive.

Upload one or more files to Drive.

• files: the file uploads (multipart)
• metadata: a JSON string containing a list of per-file metadata dicts, positionally aligned with files. Each dict may contain:
  • path — fully qualified destination path (takes precedence)
  • folder — destination folder
  • name — destination filename

Resolution logic for each file at index i:

• If path is provided, use it as the fully qualified path
• Else if folder and name are provided, combine as {folder}/{name}
• Else if folder is provided, combine as {folder}/{upload_filename}
• Else if name is provided, use /{name} (root)
• Else fall back to None (domain default behavior)