fix: wait for Proxmox resize task before VM start (v1.2.0)

- configure_vm: capture resize UPID and call wait_for_task(120s)
  before returning; prevents lock conflict when VM is started right
  after disk resize
- resize_vm_disk / resize_container_disk (x2): same fix applied
- remove unnecessary restart_vm() after manual QEMU disk resize —
  resize is a storage-layer operation and does not require a reboot;
  the auto-restart was causing a second lock conflict

Fixes: can't lock file '/var/lock/qemu-server/lock-xxx.conf' - got timeout
Fixes: command '/usr/bin/qemu-img resize' failed: got timeout

backend/app/workers/monitoring_worker.py

@@ -972,6 +972,19 @@ class MonitoringWorker:
         finally:
             db.close()
 
+    def cleanup_server_state(self, server_id: int):
+        """Remove all in-memory state for a deleted server to prevent stale data"""
+        self.last_server_states.pop(server_id, None)
+        self.last_server_alerts.pop(server_id, None)
+        # Remove all VM state entries belonging to this server
+        stale_keys = [k for k in self.last_vm_states if k.startswith(f"{server_id}:")]
+        for key in stale_keys:
+            del self.last_vm_states[key]
+        stale_alert_keys = [k for k in self.last_resource_alerts if k.startswith(f"{server_id}:")]
+        for key in stale_alert_keys:
+            del self.last_resource_alerts[key]
+        logger.info(f"[MONITORING] Cleared in-memory state for deleted server {server_id}")
+
 
 # Global worker instance
 monitoring_worker = MonitoringWorker()