Fix #3978: Pool name/category validations not being enforced.

config/danbooru_default_config.rb

@@ -144,6 +144,11 @@ module Danbooru
       2
     end
 
+    # Members cannot change the category of pools with more than this many posts.
+    def pool_category_change_limit
+      100
+    end
+
     # Whether safe mode should be enabled. Safe mode hides all non-rating:safe posts from view.
     def enable_safe_mode?(request, user)
       !!(request.host =~ /safe/ || request.params[:safe_mode] || user.enable_safe_mode?)