Phase 0.2: migrate remaining SVGs to lucide-react icons

frontend/src/components/mail/LabelManager.tsx

@@ -10,6 +10,7 @@ import { Card } from '@/components/ui/Card';
 import { EmptyState } from '@/components/ui/EmptyState';
 import { useToast } from '@/components/ui/Toast';
 import { ConfirmDialog } from '@/components/ui/ConfirmDialog';
+import { Loader2, X } from 'lucide-react';
 import {
   fetchLabels,
   createLabel,
@@ -81,10 +82,7 @@ export function LabelManager() {
   if (loading) {
     return (
       <div className="flex items-center justify-center py-8" data-testid="label-manager-loading">
-        <svg className="animate-spin h-5 w-5 text-secondary-400" fill="none" viewBox="0 0 24 24" aria-hidden="true">
-          <circle className="opacity-25" cx="12" cy="12" r="10" stroke="currentColor" strokeWidth="4" />
-          <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4z" />
-        </svg>
+        <Loader2 className="animate-spin h-5 w-5 text-secondary-400" aria-hidden="true" />
       </div>
     );
   }
@@ -155,9 +153,7 @@ export function LabelManager() {
                 data-testid={`delete-label-${label.id}`}
                 type="button"
               >
-                <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
-                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M6 18L18 6M6 6l12 12" />
-                </svg>
+                <X className="w-4 h-4" aria-hidden="true" strokeWidth={2} />
               </button>
             </div>
           ))}