feat: Task Health Check + customer_number in webhook payload

- Task model: CustomerNumber field (K-Nummer aus customers.number)
- DB: taskSelectCols joined c.number, scanTask scans CustomerNumber
- Hub: WaitForAgentOnline() polls until agent reconnects or timeout
- Scheduler: executeUpdateWithHealthCheck() waits for agent reconnect after update
  - health_check: {agent_online: bool, checked_at: RFC3339} in result
  - Status: completed_with_warning wenn Update OK aber Agent offline bleibt
- Frontend: Task-Tabelle zeigt Status-Badge (lauft/fehler/warnung/abgebr.)

frontend/src/components/AgentPanel.jsx

@@ -1821,7 +1821,13 @@ function TasksTab({ agentId, agentName }) {
               {tasks.map(t => (
                 <tr key={t.id} className={!t.active ? 'opacity-50' : ''}>
                   <td className="px-3 py-2">
-                    <span className={`inline-block w-2.5 h-2.5 rounded-full ${t.active ? 'bg-green-500' : 'bg-gray-500'}`} title={t.active ? 'Aktiv' : 'Inaktiv'} />
+                    <div className="flex items-center gap-1.5">
+                      <span className={`inline-block w-2 h-2 rounded-full flex-shrink-0 ${t.active ? 'bg-green-500' : 'bg-gray-500'}`} title={t.active ? 'Aktiv' : 'Inaktiv'} />
+                      {t.status === 'running' && <span className="text-xs px-1.5 py-0.5 rounded bg-blue-900/50 text-blue-300">lauft</span>}
+                      {t.status === 'failed' && <span className="text-xs px-1.5 py-0.5 rounded bg-red-900/50 text-red-300">fehler</span>}
+                      {t.status === 'completed_with_warning' && <span className="text-xs px-1.5 py-0.5 rounded bg-yellow-900/50 text-yellow-300" title="Update OK, aber Agent nicht wieder online">warnung</span>}
+                      {t.status === 'cancelled' && <span className="text-xs px-1.5 py-0.5 rounded bg-gray-700 text-gray-400">abgebr.</span>}
+                    </div>
                   </td>
                   <td className="px-3 py-2 text-white">{t.name || `Job #${t.id}`}</td>
                   <td className="px-3 py-2 text-gray-300 capitalize">{t.action}</td>