Add functionality to allow users to add information about author

Implements an "Add information" button on author pages that allows users to add missing biographical data directly from the profile page.

Problem Solved

• Before: Users had to navigate to Wikidata externally to add missing information.
• After: Users can add missing biographical fields through an integrated interface

When user has all fields, we simply hide the "add information" button

Features

• ✅ Smart button that only appears when fields are missing
• ✅ Dropdown showing only missing fields (Nationality, Ethnicity, Date of birth, Place of birth, Country of birth, Date of death)
• ✅ Appropriate input types: date picker for dates, text input for other fields
• ✅ Save/Cancel functionality with form validation
• ✅ Responsive design matching existing site aesthetic
• ✅ Internationalization support with new translation keys