[Feature] Support batch import of otpauth:// URLs

[toddyoe]

It would be great if the import feature could support importing multiple otpauth:// URLs at once.

For example, users could paste or upload a text file containing multiple otpauth:// links, with one URL per line, and have all accounts imported in a single operation.

This would be especially useful when migrating from other authenticator apps that can export accounts as a list of otpauth:// URLs.

Thanks!