Add dect to user profile

src/core/locale/de/LC_MESSAGES/django.po

src/core/locale/en/LC_MESSAGES/django.po

src/core/models/users.py

src/plainui/forms.py

src/plainui/jinja2/plainui/components/form_elements.html.j2

src/plainui/tests/test_views.py

src/plainui/views/user_profile.py