Add install script

Provide automated installation for Linux users to set up venv and systemd
services with proper path configuration.

Changes:
- Add install.sh with dependency checks, venv setup, and systemd configuration
- Update README to highlight automated install option

README.md

@@ -4,6 +4,12 @@ This script forwards new emails from a source IMAP account (e.g., GMX) to a dest
 
 ## Setup
 
+### Automated Install (Recommended)
+Run the install script: `./install.sh`
+
+This will set up the virtual environment, systemd services, and provide post-install instructions.
+
+### Manual Setup
 1. Copy `.env.example` to `.env` and fill in your IMAP credentials, Uptime URLs, and settings.
 
 2. Create virtual environment: `python -m venv venv`