Add BBS::Color module with c() helper

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/bbs/color.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+module BBS
+  module Color
+    COLORS = {
+      reset: "\e[0m",    gray:    "\e[0;37m", yellow:  "\e[0;33m",
+      white: "\e[1;37m", blue:    "\e[0;34m", cyan:    "\e[0;36m",
+      green: "\e[1;32m", magenta: "\e[0;35m", red:     "\e[1;31m"
+    }.freeze
+
+    module_function
+
+    def c(color, text)
+      "#{COLORS.fetch(color)}#{text}#{COLORS[:reset]}"
+    end
+  end
+end