feat: replace browser confirm with gui modal for delete

frontend/src/components/FileExplorer.tsx

@@ -244,6 +244,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
   const [draggedFile, setDraggedFile] = useState<string | null>(null);
   const [uploads, setUploads] = useState<UploadProgress[]>([]);
   const [toasts, setToasts] = useState<Toast[]>([]);
+  const [deleteConfirm, setDeleteConfirm] = useState<{ type: 'single' | 'multiple'; file?: FileItem; count?: number } | null>(null);
 
   function showToast(message: string, type: 'success' | 'error' | 'info' = 'success') {
     const id = Date.now() + Math.random();
@@ -384,7 +385,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
         e.preventDefault();
         navigateUp();
       } else if (e.key === 'Delete') {
-        deleteSelected();
+        requestDeleteSelected();
       } else if (e.key === 'a' && (e.ctrlKey || e.metaKey)) {
         e.preventDefault();
         selectAll();
@@ -613,18 +614,29 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
     setSelectedFiles(new Set(files.map(f => f.path)));
   }
 
-  async function deleteSelected() {
+  function requestDeleteSelected() {
     if (selectedFiles.size === 0) return;
-    if (!confirm(`Move ${selectedFiles.size} items to trash?`)) return;
+    setDeleteConfirm({ type: 'multiple', count: selectedFiles.size });
+  }
+
+  async function executeDeleteSelected() {
     const count = selectedFiles.size;
     for (const path of selectedFiles) {
       await api.deleteFile(path);
     }
     setSelectedFiles(new Set());
     loadFiles(undefined, true);
+    setDeleteConfirm(null);
     showToast(`Deleted ${count} item${count > 1 ? 's' : ''}`);
   }
 
+  async function executeDeleteSingle(file: FileItem) {
+    await api.deleteFile(file.path);
+    loadFiles(undefined, true);
+    setDeleteConfirm(null);
+    showToast(`Deleted ${file.name}`);
+  }
+
   async function handlePin(file: FileItem) {
     await api.togglePin(file.path);
     loadFiles(undefined, true);
@@ -1578,7 +1590,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
               <button
                 className="p-2 hover:bg-red-500/10 rounded-lg transition-colors flex items-center gap-2 text-sm text-red-500"
                 title="Delete Selected"
-                onClick={() => deleteSelected()}
+                onClick={() => requestDeleteSelected()}
               >
                 <Trash2 className="w-4 h-4" />
               </button>
@@ -1693,12 +1705,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
                   label="Move to Trash"
                   danger
                   onClick={() => {
-                    if (confirm(`Move ${contextMenu.file.name} to trash?`)) {
-                      api.deleteFile(contextMenu.file.path).then(() => {
-                        loadFiles(undefined, true);
-                        showToast(`Deleted ${contextMenu.file.name}`);
-                      });
-                    }
+                    setDeleteConfirm({ type: 'single', file: contextMenu.file });
                     setContextMenu(null);
                   }}
                 />
@@ -1857,6 +1864,47 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
         )}
       </AnimatePresence>
 
+      <AnimatePresence>
+        {deleteConfirm && (
+          <div className="fixed inset-0 z-[120] flex items-center justify-center bg-black/50 backdrop-blur-sm">
+            <motion.div
+              initial={{ opacity: 0, scale: 0.95 }}
+              animate={{ opacity: 1, scale: 1 }}
+              exit={{ opacity: 0, scale: 0.95 }}
+              className="w-full max-w-md overflow-hidden rounded-2xl shadow-xl"
+              style={{ backgroundColor: 'var(--color-bg-primary)', border: '1px solid var(--color-border)' }}
+            >
+              <div className="p-6">
+                <h2 className="text-xl font-bold mb-2" style={{ color: 'var(--color-text-primary)' }}>Move to Trash?</h2>
+                <p className="mb-6" style={{ color: 'var(--color-text-secondary)' }}>
+                  {deleteConfirm.type === 'multiple' 
+                    ? `Are you sure you want to move ${deleteConfirm.count} items to the trash?`
+                    : `Are you sure you want to move ${deleteConfirm.file?.name} to the trash?`}
+                </p>
+                <div className="flex justify-end gap-3">
+                  <button
+                    onClick={() => setDeleteConfirm(null)}
+                    className="px-4 py-2 rounded-lg text-sm font-medium transition-colors hover:opacity-80"
+                    style={{ backgroundColor: 'var(--color-bg-tertiary)', color: 'var(--color-text-primary)' }}
+                  >
+                    Cancel
+                  </button>
+                  <button
+                    onClick={() => {
+                      if (deleteConfirm.type === 'multiple') executeDeleteSelected();
+                      else if (deleteConfirm.file) executeDeleteSingle(deleteConfirm.file);
+                    }}
+                    className="px-4 py-2 rounded-lg text-sm font-medium transition-colors hover:opacity-90 bg-red-500 text-white"
+                  >
+                    Move to Trash
+                  </button>
+                </div>
+              </div>
+            </motion.div>
+          </div>
+        )}
+      </AnimatePresence>
+
       <AnimatePresence>
         {showTrashModal && (
           <div className="fixed inset-0 z-[120] flex items-center justify-center bg-black/50 backdrop-blur-sm">