feat: dim whitespace markers and configure scope and newlines

examples/config.rb

@@ -7,7 +7,8 @@ Vamp.configure do |config|
   config.git_blame = true # false disables current-line inline blame
   config.scroll_distance = 0 # nonnegative edge distance, or nil to center
   config.highlight_trailing_whitespace = false # true marks line-end whitespace in red
-  config.whitespace_characters = {} # opt in: { " " => "·", "\t" => "→", "\u00a0" => "⍽" }
+  config.whitespace_characters = {} # opt in: { " " => "·", "\t" => "→", "\n" => "↵" }
+  config.whitespace_scope = "all" # or "leading" for indentation only; newline markers remain independent
   config.file_explorer_side = "right"
   config.file_explorer_view = "tree"
   config.file_picker_view = "tree"