feat(vm): hoàn tiền khi cấp VM lỗi, theo dõi job queue, uuid dịch vụ cho ticket, chuẩn hoá RAM addon

- VmProvisionException/VmProvisionRefund xử lý lỗi cấp phát VM
- QueueJobInspector + QueueMonitorController xem chi tiết job
- Thêm service uuid cho ticket, thời lượng cho activity_logs
- Migration chuẩn hoá RAM addon sang MB, trạng thái deleting cho snapshot

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/Services/VirtualMachine/VmIpReservationService.php

@@ -18,6 +18,11 @@ use Illuminate\Support\Facades\Log;
  */
 class VmIpReservationService
 {
+    public function hasFreeIp(): bool
+    {
+        return $this->availableIps()->exists();
+    }
+
     /**
      * @return array{reservation:ModuleIpAddress,ip_pool_id:int,gateway:string,cidr:int}|null
      */
@@ -25,8 +30,7 @@ class VmIpReservationService
     {
         return DB::transaction(function () use ($networkId, $hostId, $dns) {
             // ip_pools.status is the single source of truth for availability.
-            $ipPool = IpPool::where('module_network_id', $networkId)
-                ->whereIn('status', ['free', 'reserved'])
+            $ipPool = $this->availableIps()
                 ->lockForUpdate()
                 ->inRandomOrder()
                 ->first();
@@ -44,7 +48,6 @@ class VmIpReservationService
             // module_ip_address mirrors ip_pools — update the existing synced row
             // (created when the IP was added to ip_pools) instead of inserting a new one.
             $reservation = ModuleIpAddress::where('ip', $ipPool->ip_address)
-                ->where('module_network_id', $networkId)
                 ->lockForUpdate()
                 ->first();
 
@@ -101,6 +104,13 @@ class VmIpReservationService
         });
     }
 
+    private function availableIps()
+    {
+        return IpPool::whereIn('status', ['free', 'reserved'])
+            ->whereNotNull('gateway')
+            ->where('gateway', '!=', '');
+    }
+
     public function freeIpsInNetwork(int $networkId)
     {
         return IpPool::where('module_network_id', $networkId)