Fix disabled named color reflection

[OskarEichler]

Summary

Make disabled presenters accurately report their supported named color methods, and add disabled-mode parity for the default named color introduced on current master.

Reproduction

Rainbow::Wrapper.new(false).wrap('x').aqua works, but respond_to?(:aqua) returns false and method(:aqua) raises. Ruby passes the include_private boolean to respond_to_missing?; treating that boolean as a normal method argument makes the current args.empty? guard fail.

Verification

• Existing suite: 220 examples, 0 failures on Ruby 3.2.11 and 4.0.6.
• RuboCop: 15 files, 0 offenses on both Rubies.
• External model: 1,325 reflection, method lookup, invocation, unknown-method, privacy and wrong-arity checks per Ruby across all ANSI/X11 names and string/symbol lookup forms.
• Rebuilt gem: 14 expected files and successful packaged loads on both Rubies.
• No test files changed.

Compatibility

No breaking change. Previously supported disabled-mode calls now expose the Ruby reflection contract they already implied.