Add GitHub Actions workflow for S3 deployment

- Automated deployment script upload to public S3 bucket
- Uses GitHub OIDC for secure AWS authentication
- Updates README with current S3 URLs automatically
- Enables deployment from private repository
- Uploads systemd service and Caddyfile configurations

README.md

@@ -65,7 +65,7 @@ PORT=3000
 
 1. **Run the deployment script on your server:**
    ```bash
-   curl -sSL https://raw.githubusercontent.com/deco/ice/main/scripts/deploy.sh | bash
+   curl -sSL https://your-bucket-name.s3.amazonaws.com/icewatch/deploy.sh | bash
    ```
 
 2. **Deploy your application:**