feat: allow customization of django admin backend

The login dialog header and the page header of the steering admin interface are confusing because the naming and URLs don’t match up with user expectations.

This adds sensible defaults and allows administrators to customize the values for their specific needs.

program/admin.py

@@ -21,6 +21,11 @@ from program.models import (
     Type,
 )
 
+# This URL is used in the Django admin backend to "View [the] Site".
+# Steering doesn’t have a public facing website so it doesn’t make sense to keep the default.
+admin.site.site_url = settings.SITE_WEBSITE_URL
+admin.site.site_header = settings.SITE_NAME
+
 
 @admin.register(Category, FundingCategory, MusicFocus, Topic, Type)
 class AdminWithNameSlugIsActive(admin.ModelAdmin):