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/bin/install_homebrew_casks

@@ -0,0 +1,21 @@
+#! /usr/bin/env bash
+
+# Installs Homebrew Casks (GUI applications).
+
+# Browsers
+brew install --cask eloston-chromium
+
+# Communication
+brew install --cask deepl
+brew install --cask element
+brew install --cask signal
+
+# Cloud & Sync
+brew install --cask nextcloud
+brew install --cask proton-drive
+brew install --cask proton-mail
+brew install --cask protonvpn
+
+# Development
+brew install --cask nova
+brew install --cask transmit