Allow users to keep anonymous scans after signing in

[DevOlabode]

Summary

Give users the option to preserve scans completed before signing in.

Problem

Users can perform scans without signing in, but those scans are not currently offered for migration after authentication.

Proposed Work

Detect locally available anonymous scans.
Prompt users after sign-in.
Allow users to import or discard those scans.
Save imported scans into the authenticated account.

Acceptance Criteria

Users can choose whether to keep anonymous scans.
Imported scans appear in the authenticated account.