Enable management of auto-extracted contacts (view, merge, remove)

When Akiflow auto-extracts contacts from sources like calendar events, users have no way to manage them. This leads to clutter—especially for users who change email domains (e.g., Google to Microsoft), resulting in duplicate entries for the same person. These contacts persist indefinitely and crowd autocomplete suggestions. The only current workaround—deleting old events and reconnecting accounts—is time-consuming and error-prone. Providing tools to view, merge, or remove these contacts would streamline contact management and improve the user experience.