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/Gemfile

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+ruby file: ".ruby-version"
+
+source "https://rubygems.org"
+
+gem "caliber", "~> 0.82"
+gem "debug", "~> 1.11"
+gem "git-lint", "~> 10.0"
+gem "rake", "~> 13.3"