fix: use correct server URL instead of localhost

AgentService now replaces 'localhost' in the server URL with
sysadmin.lan before sending to the remote agent. Also added
URL/hostname debug output to the agent startup log.

install/agent-install.sh

@@ -82,12 +82,20 @@ EOF
     echo "$code"
 }
 
-echo "ServerManager Agent started (interval: ${INTERVAL}s)"
+echo "ServerManager Agent started"
+echo "  Server: $SERVER_URL/api/metrics/push"
+echo "  Interval: ${INTERVAL}s"
+echo "  Host: $(hostname)"
 sleep 2
 while true; do
     collect_metrics
     http_code=$(push_metrics)
     echo "[$(date)] HTTP $http_code"
+    if [ "$http_code" = "200" ]; then
+        true
+    elif [ "$http_code" = "0" ]; then
+        echo "  curl failed — check SERVER_URL=$SERVER_URL"
+    fi
     sleep "$INTERVAL"
 done
 AGENTSCRIPT