feat: add aggregated resource usage chart to dashboard

src/Services/MonitoringService.php

@@ -173,6 +173,29 @@ class MonitoringService
         );
     }
 
+    public function getAggregatedHistoricalMetrics(array $serverIds, int $hours = 24): array
+    {
+        if (empty($serverIds)) {
+            return [];
+        }
+        $placeholders = implode(',', array_fill(0, count($serverIds), '?'));
+        $params = $serverIds;
+        $params[] = $hours;
+        return $this->db->fetchAll(
+            "SELECT
+                DATE_FORMAT(created_at, '%Y-%m-%d %H:%i:00') as time_bucket,
+                AVG(cpu_usage) as avg_cpu,
+                AVG(ram_usage) as avg_ram,
+                AVG(disk_usage) as avg_disk
+             FROM monitoring_history
+             WHERE server_id IN ({$placeholders})
+               AND created_at >= DATE_SUB(NOW(), INTERVAL ? HOUR)
+             GROUP BY time_bucket
+             ORDER BY time_bucket ASC",
+            $params
+        );
+    }
+
     public function getDashboardStats(?array $serverIds = null): array
     {
         $where = '';