Unknown option for date found for cultural materials

**Given** a valid site with historical (pre-BCAP) dates on cultural material entries
**When** viewing the Details screen
or viewing the info in the edit view
**Then** the dates are shown as part of the Details column
and newly added records no longer required a date to be entered here

**AC**:
- [ ] Historical (pre-BCAP) materials have the date merged into the Details column (see mockup)
- [ ] Date (in the Details field) can be edited when editing the site
- [ ] Date no longer required when adding a new cultural material

**Note**:
In BCAP, the date is recorded as part of the site visit and not the artifact itself

Start at the cultural material Details screen and edit view entry points, then trace how historical pre-BCAP dates are displayed and how dates are validated when adding records. Done means the date appears in Details, remains editable there, and is no longer required for new cultural material records.

Written by the indexing model from the issue text.