ClovaKey

Fixes the Google Authenticator import failing at the final step: the wizard was cancelling its own import session when it advanced to the review list.

Importing from Google Authenticator can now be retried: a failed import keeps the session instead of discarding it, and a single rejected account no longer abandons the rest.

Adds a second QR decoder so dense Google Authenticator export codes that the first decoder cannot read are still imported.

Fixes importing from Google Authenticator: export QR codes that are light-on-dark (a screenshot of a dark-themed screen) or densely packed now decode correctly.