Add clear plate confirmation between queued prints

The print scheduler previously treated FINISH/FAILED as idle states
and would auto-start the next queued print before the user cleared
the build plate. Now requires explicit user confirmation via a
"Clear Plate & Start Next" button on the printer card. Uses an
in-memory plate-cleared flag — no MQTT command needed since the
scheduler's start_print overrides the printer state.

frontend/src/components/Layout.tsx

@@ -375,7 +375,7 @@ export function Layout() {
           break;
       }
     }
-  }, [navigate, orderedSidebarIds, navItemsMap]);
+  }, [navigate, orderedSidebarIds, navItemsMap, extLinksMap]);
 
   useEffect(() => {
     document.addEventListener('keydown', handleKeyDown);

frontend/src/components/PrinterQueueWidget.tsx

@@ -1,11 +1,15 @@
-import { useQuery } from '@tanstack/react-query';
-import { Clock, Calendar, ChevronRight } from 'lucide-react';
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { Clock, Calendar, ChevronRight, Loader2, CircleCheck } from 'lucide-react';
 import { Link } from 'react-router-dom';
+import { useTranslation } from 'react-i18next';
 import { api } from '../api/client';
+import { useAuth } from '../contexts/AuthContext';
+import { useToast } from '../contexts/ToastContext';
 import { parseUTCDate } from '../utils/date';
 
 interface PrinterQueueWidgetProps {
   printerId: number;
+  printerState?: string | null;
 }
 
 function formatRelativeTime(dateString: string | null): string {
@@ -22,13 +26,29 @@ function formatRelativeTime(dateString: string | null): string {
   return date.toLocaleDateString();
 }
 
-export function PrinterQueueWidget({ printerId }: PrinterQueueWidgetProps) {
+export function PrinterQueueWidget({ printerId, printerState }: PrinterQueueWidgetProps) {
+  const { t } = useTranslation();
+  const queryClient = useQueryClient();
+  const { showToast } = useToast();
+  const { hasPermission } = useAuth();
   const { data: queue } = useQuery({
     queryKey: ['queue', printerId, 'pending'],
     queryFn: () => api.getQueue(printerId, 'pending'),
     refetchInterval: 30000,
   });
 
+  const clearPlateMutation = useMutation({
+    mutationFn: () => api.clearPlate(printerId),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['queue', printerId] });
+      queryClient.invalidateQueries({ queryKey: ['printerStatus', printerId] });
+      showToast(t('queue.clearPlateSuccess'), 'success');
+    },
+    onError: (err: Error) => {
+      showToast(err.message, 'error');
+    },
+  });
+
   const nextItem = queue?.[0];
   const totalPending = queue?.length || 0;
 
@@ -36,6 +56,48 @@ export function PrinterQueueWidget({ printerId }: PrinterQueueWidgetProps) {
     return null;
   }
 
+  const needsClearPlate = printerState === 'FINISH' || printerState === 'FAILED';
+
+  if (needsClearPlate) {
+    return (
+      <div className="mb-3 p-3 bg-bambu-dark rounded-lg border border-yellow-400/30">
+        <div className="flex items-center gap-3 mb-2">
+          <Calendar className="w-5 h-5 text-yellow-400 flex-shrink-0" />
+          <div className="min-w-0 flex-1">
+            <p className="text-xs text-bambu-gray">{t('queue.nextInQueue')}</p>
+            <p className="text-sm text-white truncate">
+              {nextItem?.archive_name || `Archive #${nextItem?.archive_id}`}
+            </p>
+          </div>
+          {totalPending > 1 && (
+            <span className="text-xs px-1.5 py-0.5 bg-yellow-400/20 text-yellow-400 rounded flex-shrink-0">
+              +{totalPending - 1}
+            </span>
+          )}
+        </div>
+        {clearPlateMutation.isSuccess ? (
+          <div className="w-full py-2 px-3 rounded-lg bg-bambu-green/10 border border-bambu-green/20 text-bambu-green text-sm flex items-center justify-center gap-2">
+            <CircleCheck className="w-4 h-4" />
+            {t('queue.plateReady')}
+          </div>
+        ) : (
+          <button
+            onClick={() => clearPlateMutation.mutate()}
+            disabled={clearPlateMutation.isPending || !hasPermission('printers:control')}
+            className="w-full py-2 px-3 rounded-lg bg-bambu-green/20 border border-bambu-green/40 text-bambu-green hover:bg-bambu-green/30 transition-colors text-sm font-medium flex items-center justify-center gap-2 disabled:opacity-50"
+          >
+            {clearPlateMutation.isPending ? (
+              <Loader2 className="w-4 h-4 animate-spin" />
+            ) : (
+              <CircleCheck className="w-4 h-4" />
+            )}
+            {t('queue.clearPlate')}
+          </button>
+        )}
+      </div>
+    );
+  }
+
   return (
     <Link
       to="/queue"
@@ -45,7 +107,7 @@ export function PrinterQueueWidget({ printerId }: PrinterQueueWidgetProps) {
         <div className="flex items-center gap-3 min-w-0 flex-1">
           <Calendar className="w-5 h-5 text-yellow-400 flex-shrink-0" />
           <div className="min-w-0 flex-1">
-            <p className="text-xs text-bambu-gray">Next in queue</p>
+            <p className="text-xs text-bambu-gray">{t('queue.nextInQueue')}</p>
             <p className="text-sm text-white truncate">
               {nextItem?.archive_name || `Archive #${nextItem?.archive_id}`}
             </p>