The accommodation field in the registration form is missing both front- and back-end validation. While the widget prevents selecting dates outside of the configured range, it doesn't prevent typing them.

To Reproduce
Steps to reproduce the behavior:

1. Add an accommodation field to a registration form.
2. Add an accommodation option and configure arrival/departure date ranges.
3. Go to the registration form as a participant.
4. Type arrival and departure dates outside of the range.
5. Submit the form.
6. Observe how the form submission succeeds while it shouldn't.

Expected behavior

• The backend shouldn't admit a form submission with arrival/departure dates outside of the configured range.
• The frontend should display an error as soon as an invalid date is typed in the field.

Screenshots

Configured arrival/departure dates:

Accommodation arrival/departure dates selection widget, showing the right range:

Invalid dates typed into the fields:

Registration summary containing invalid dates: