Fix code scanning alert no. 3: Incomplete string escaping or encoding

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

app/services/open_graph_image_generator.rb

@@ -145,6 +145,6 @@ def download_image(url)
   end
 
   def escape_text(text)
-    text.gsub("'", "\\'")
+    text.gsub("\\", "\\\\\\").gsub("'", "\\\\'")
   end
 end