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_app_store

@@ -0,0 +1,17 @@
+#! /usr/bin/env bash
+
+# Installs App Store software.
+
+# Affinity Suite
+mas install 1616831348  # Affinity Designer 2
+mas install 1616822987  # Affinity Photo 2
+mas install 1606941598  # Affinity Publisher 2
+
+# Productivity
+mas install 1352778147  # Bitwarden
+mas install 424389933   # Final Cut Pro
+mas install 1503970375  # Invoice Ninja
+mas install 409203825   # Numbers
+mas install 409201541   # Pages
+mas install 1503446680  # PastePal
+mas install 1579902068  # xSearch