fix(gem): guard Rails-only debug hook in Base component

Author: djalmaaraujo

gem/lib/ruby_ui/base.rb

@@ -19,7 +19,7 @@ def default_attrs
       {}
     end
 
-    if Rails.env.development?
+    if defined?(Rails) && Rails.env.development?
       def before_template
         comment { "Before #{self.class.name}" }
       end