Flatten directory structure and update documentation

- Moved all files from mac_os/ subdirectory to repository root
- Updated README.adoc to reflect simplified architecture
- Updated QUICK_INSTALL.md with all current apps
- Added claude-cli to install.sh and bin/install_homebrew_formulas
- Repository now shows clean file structure without nested mac_os folder
- Documentation now accurately describes opinionated installer approach

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

bin/install_app_store

@@ -0,0 +1,21 @@
+#! /usr/bin/env bash
+
+# Installs App Store software.
+
+set -o nounset
+set -o errexit
+set -o pipefail
+IFS=$'\n\t'
+
+# Check that mas CLI is installed
+check_mas_install
+
+# Productivity
+mas install 1352778147  # Bitwarden
+mas install 1503970375  # Invoice Ninja
+mas install 409203825   # Numbers
+mas install 409201541   # Pages
+mas install 1503446680  # PastePal
+mas install 1579902068  # xSearch
+
+printf "\n✅ Mac App Store applications installation complete!\n"