Initial setup: mac_os installer with custom config

Contains both components needed for Mac setup:
- mac_os/: Installer scripts (from bkuhlmann/mac_os)
- mac_os-config/: Custom app configuration

Configured apps:
- Homebrew formulas: atuin, bash, ffmpeg, mas, mole, node, rename, ykman
- Homebrew casks: chromium, deepl, element, nextcloud, nova, proton suite, signal, transmit
- App Store: Affinity suite, Bitwarden, Final Cut Pro, Invoice Ninja, iWork, PastePal, xSearch

Usage: cd mac_os && ./bin/run

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

mac_os-config/Rakefile

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require "git/lint/rake/register"
+require "rubocop/rake_task"
+
+Git::Lint::Rake::Register.call
+RuboCop::RakeTask.new
+
+desc "Run code quality checks"
+task quality: %i[git_lint rubocop]
+
+task default: :quality