Render asset credit inside the gallery lightbox correctly

GLightbox's own selector-based description feature never actually
resolved a selector in three different attempts -- literal text,
then a resolved-but-empty div, then apparently not firing at all
against the installed (unversioned) build. Replaced with a small
afterSlideLoad handler that reads a plain data-credit-selector
attribute and copies the real element's HTML into the slide's
description area directly, depending only on GLightbox handing back
a real DOM node per slide -- a much smaller contract than trusting
its own caption-resolution feature.

Renamed the credit div's class from glightbox-desc, since that name
is reserved by the library's own bundled CSS (display: none
!important) and can't be reliably overridden from here.

Also: distinguishes the credit line and the "N Bilder" caption from
ordinary body text (italic, muted, matching .author_and_date's
existing convention), and makes the lightbox's caption card follow
the site's light/dark toggle via Canvas/CanvasText, since the
library's bundled theme never adapts to it on its own.

1 files changed, 4 insertions, 0 deletions

diff --git a/app/models/asset.rb b/app/models/asset.rb
index 8bea1b3..4a295d8 100644
--- a/app/models/asset.rb
+++ b/app/models/asset.rb
@@ -15,4 +15,8 @@ class Asset < ApplicationRecord
   def image?
     IMAGE_CONTENT_TYPES.include?(upload_content_type)
   end
+
+  def has_credit?
+    creator.present? || source_url.present? || license_key.present?
+  end
 end