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

src/Services/AgentService.php

@@ -37,10 +37,13 @@ class AgentService
         $agentKey = $server['agent_key'];
         $serverUrl = rtrim((App::getConfig()['app']['url'] ?? ''), '/');
 
-        if (empty($serverUrl)) {
+        if (empty($serverUrl) || str_contains($serverUrl, 'localhost')) {
-            $serverUrl = ($_SERVER['HTTPS'] ?? '' === 'on' ? 'https://' : 'http://') . ($_SERVER['HTTP_HOST'] ?? 'localhost');
+            $serverUrl = ($_SERVER['HTTPS'] ?? '' === 'on' ? 'https://' : 'http://') . ($_SERVER['HTTP_HOST'] ?? 'sysadmin.lan');
         }
 
+        // Replace localhost with actual hostname if still localhost
+        $serverUrl = preg_replace('/https?:\/\/localhost(:\d+)?/', 'http://sysadmin.lan$1', $serverUrl);
+
         $scriptPath = $this->basePath . '/install/agent-install.sh';
 
         if (!file_exists($scriptPath)) {