[DwC export]: Add 'Darwin Core' section to Schema Configuration page

[grantfitzsimmons]

Goal

In the Schema Configuration interface, add a Darwin Core section below the Specify field description that shows the mapped DwC term(s), their description, IRI, and vocabulary.

Background

Helps users understand which DwC concepts a Specify field relates to without leaving the Schema Config page, reinforcing the connection between the data model and the published vocabulary.

Acceptance Criteria

• A "Darwin Core" collapsible section appears below the field description in Schema Config.
• The section is collapsed by default and expands on click.
• When expanded, it shows: term name, full IRI, description, and vocabulary for each mapped term.
• If multiple DwC terms map to the same field (per the JSON), each is shown as a separate list item.
• If no terms are mapped to a field, the section shows: "No Darwin Core terms mapped to this field."
• The section is read-only in Schema Config.