The field name 'date' in EventUpdate shadowed the 'date' type from
datetime, causing Pydantic v2 to interpret Optional[date] as
Optional[None] — rejecting all non-null values with a 422 error.
Fix: rename import to 'date as _date' and use '_date' in all
annotations. Also improve error handling in admin forms to properly
display 422 validation error messages.
Co-Authored-By: Claude <noreply@anthropic.com>
kfj001
