Add mac launcher, py2app setup, and build script

Co-authored-by: Copilot <[email protected]>

README.md

@@ -30,6 +30,20 @@ docker compose up
 
 Open [http://localhost:5000](http://localhost:5000) in your browser.
 
+### Building a macOS .app (Standalone)
+
+A convenience build script is provided to create a standalone macOS application bundle that includes a Python runtime and the app. Note: the build must be run on macOS and requires internet access to install dependencies.
+
+Run the following on your Mac:
+
+```bash
+chmod +x build_mac.sh
+./build_mac.sh
+```
+
+The built .app will appear in dist/ (example: `dist/mac_launcher.app`). Double-click the `.app` to launch; it will start a local web server and open your default browser to the UI.
+
+
 ## Usage
 
 1. The date range defaults to the previous week (Mon–Sat).