bingo: optional prose per datacenter page

The datacenter pages carry only generated sentences, which is thin
content to rank on. Migration 015 adds about_ru/en/uk, edited in the
admin form and rendered as paragraphs below the facts.

There is deliberately no fallback to ru: Russian prose on the English
page would hurt more than an absent paragraph.

Assisted-by: Claude:opus-5

lib/bingo.rb

@@ -143,6 +143,11 @@ module Bingo
       key.delete_prefix(Photo::PREFIX)
     end
 
+    # Paragraphs of the datacenter page's prose in exactly this locale.
+    def about(locale)
+      self[:"about_#{locale}"].to_s.strip.split(/\n\s*\n/).map(&:strip)
+    end
+
     # 1200x630 JPEG for og:image (every preview client renders it); the
     # webp dialog variant until it exists.
     def og_file