Prepare macOS package and improve output handling

install.command

@@ -0,0 +1,36 @@
+#!/bin/bash
+
+set -u
+
+SCRIPT_DIR="$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)"
+
+pause_on_exit() {
+    printf '\nPress Return to close this window...'
+    read -r _
+}
+trap pause_on_exit EXIT
+
+fail() {
+    printf '\nError: %s\n' "$1" >&2
+    exit 1
+}
+
+cd "$SCRIPT_DIR" || fail "Could not open the project directory."
+
+command -v python3 >/dev/null 2>&1 || fail \
+    "python3 was not found. Install Python 3, then run this installer again."
+
+if [ ! -x ".venv/bin/python" ] || ! ".venv/bin/python" -m pip --version >/dev/null 2>&1; then
+    printf 'Creating virtual environment...\n'
+    python3 -m venv --clear .venv || fail \
+        "Could not create .venv. Make sure your Python installation includes venv support."
+else
+    printf 'Using existing virtual environment.\n'
+fi
+
+printf 'Installing dependencies...\n'
+".venv/bin/python" -m pip install -r requirements.txt || fail \
+    "Dependency installation failed."
+
+printf '\nInstallation completed successfully.\n'
+printf 'You can now run radioeins-top100.command.\n'