Rename project from system-stats-daemon to systant

- Updated all module names from SystemStatsDaemon to Systant
- Renamed application config from :system_stats_daemon to :systant
- Updated service files and documentation
- Release binary now at _build/prod/rel/systant/bin/systant

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

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

systant.service

@@ -0,0 +1,26 @@
+[Unit]
+Description=Systant MQTT Daemon
+After=network.target
+
+[Service]
+Type=exec
+User=root
+Group=root
+ExecStart=/opt/systant/bin/systant start
+ExecStop=/opt/systant/bin/systant stop
+Restart=always
+RestartSec=5
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=systant
+WorkingDirectory=/opt/systant
+
+# Security settings - still apply restrictions where possible
+NoNewPrivileges=true
+PrivateTmp=true
+ProtectHome=true
+# Don't use ProtectSystem=strict since we need to read system stats
+ProtectSystem=false
+
+[Install]
+WantedBy=multi-user.target