fix: gallery lightbox doesn't always load

Lightbox may not load in case of gallery shortcode contained within `text` field of a landing page block (v2 blocks).

Fix #2972

modules/wowchemy/layouts/partials/functions/parse_block_v2.html

@@ -11,11 +11,18 @@
   {{ errorf "%s uses a `%s` block but the `%s` block was not found at `layouts/partials/%s`" $block.File.Path $block_type $block_type $block_path }}
 {{ end }}
 
-{{/* Workaround to make Hugo's .Page.Store.Set cascade up to the parent of headless pages */}}
+{{/* Mermaid block: Workaround to make Hugo's .Page.Store.Set cascade up to the parent of headless pages */}}
 {{ if $block.Page.Store.Get "has_mermaid" }}
   {{ $page.Page.Store.Set "has_mermaid" true }}
 {{ end }}
 
+{{/* Gallery block: Workaround to make Hugo's .Page.Store.Set cascade up from page blocks to the page context */}}
+{{/* Unfortunately, `.HasShortcode "gallery"` won't accept string input, only page context - so irrelevant here */}}
+{{/* Therefore, must do our own search for shortcodes within the `text` string */}}
+{{ if (gt (len (findRE `\{\{< gallery` $block.content.text 1)) 0) }}
+  {{ $page.Page.Store.Set "has_gallery" true }}
+{{ end }}
+
 {{/* Begin widget styling */}}
 {{ $bg := $block.design.background }}
 {{ $style := "" }}

modules/wowchemy/layouts/partials/site_head.html

@@ -95,7 +95,6 @@
         {{ $has_gallery = true }}
       {{ end }}
     {{ end }}
-    {{ $scr.Set "HasNestedGalleryShortcode" $has_gallery }}
     {{ if $has_gallery | or site.Params.require_fancybox }}
       {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\" media=\"print\" onload=\"this.media='all'\">" (printf $css.fancybox.url $css.fancybox.version) $css.fancybox.sri | safeHTML }}
     {{ end }}

modules/wowchemy/layouts/partials/site_js.html

@@ -23,7 +23,7 @@
   {{ end }}
 
   {{/* Workaround `.HasShortcode "gallery"` detection issue on `home/` WidgetPage v1 */}}
-  {{ if ($scr.Get "HasNestedGalleryShortcode") | or site.Params.require_fancybox }}
+  {{ if (.Page.Store.Get "has_gallery") | or site.Params.require_fancybox }}
     {{ printf "<script src=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\"></script>" (printf $js.fancybox.url $js.fancybox.version) $js.fancybox.sri | safeHTML }}
   {{ end }}