Add UV run support and systemd service installer

**UV Integration:**
- Updated pyproject.toml with [tool.uv.scripts]
- Added 'uv run start' to launch wedding phone
- Added 'uv run test' to run audio tests
- Refactored main code into main() function
- Added proper entry point for package installation

**Systemd Service:**
- Created wedding-phone.service template
- Service runs with UV for dependency management
- Automatic restart on failure
- Proper security hardening (NoNewPrivileges, PrivateTmp)
- GPIO and audio group access configured

**Service Installer:**
- Created install_service.sh automated installer
- Auto-detects project path and user
- Checks for UV installation and dependencies
- Configures service file with correct paths
- Option to enable and start immediately
- Provides helpful command reference

**Installer Features:**
- Validates config.json exists (creates from example if missing)
- Installs UV dependencies automatically
- Updates service file paths dynamically
- Color-coded output for clarity
- Error checking at each step
- Clean installation process

**Usage:**
```bash
# Run directly with UV
uv run start

# Install as system service
./install_service.sh

# Service management
sudo systemctl start wedding-phone
sudo systemctl stop wedding-phone
sudo journalctl -u wedding-phone -f
```

**Documentation:**
- Updated README with UV commands
- Added service installation guide
- Removed old manual systemd instructions
- Added service management commands
- Updated file structure documentation

**Benefits:**
- Easier to run (single command)
- Automatic startup on boot
- Better dependency management
- Professional service integration
- Simplified installation process

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

wedding-phone.service

@@ -0,0 +1,24 @@
+[Unit]
+Description=Wedding Phone - Vintage Rotary Phone Audio System
+After=network.target sound.target
+Wants=network.target sound.target
+
+[Service]
+Type=simple
+User=pi
+Group=pi
+WorkingDirectory=/home/pi/wedding-phone
+Environment="PATH=/home/pi/.local/bin:/usr/local/bin:/usr/bin:/bin"
+ExecStart=/usr/bin/env uv run start
+Restart=always
+RestartSec=10
+
+# Security hardening
+NoNewPrivileges=true
+PrivateTmp=true
+
+# Allow GPIO access
+SupplementaryGroups=gpio audio
+
+[Install]
+WantedBy=multi-user.target