feat: add configurable Ctrl+j/k list navigation

src/ruby_host.rb

@@ -38,7 +38,7 @@ module Vamp
   end
 
   module Modes
-    %w[normal insert command search visual].each do |name|
+    %w[normal insert command search visual selection].each do |name|
       mode = Mode.new(name.freeze).freeze
       define_singleton_method(name) { mode }
     end