feat(deploy): add systemd service configuration and update deployment documentation

Add psagentia.service file for systemd service management and update DEPLOY.md
with new deployment paths, user service option (without sudo), and improved
service management commands for both system and user-level installations.

psagentia.service

@@ -0,0 +1,17 @@
+[Unit]
+Description=PsAgentIA - Personal Agent IA Conversacional
+After=network.target
+
+[Service]
+Type=simple
+User=marco
+WorkingDirectory=/home/marco/PsAgentIA/app
+Environment="PATH=/home/marco/PsAgentIA/app/venv/bin:/usr/local/bin:/usr/bin:/bin"
+ExecStart=/home/marco/PsAgentIA/app/venv/bin/python3 /home/marco/PsAgentIA/app/psagentia_agent.py
+Restart=always
+RestartSec=10
+StandardOutput=journal
+StandardError=journal
+
+[Install]
+WantedBy=multi-user.target