Bulk selection UI and import-review modal

Transactions gain a checkbox column with select-all; a bulk bar offers
assign-category, defer/restore and delete (confirmed) via the new bulk
endpoint, with toasts and invalidation. The paste-import modal now
lists each skipped duplicate with the matched existing row and offers
'Importar duplicados de todos modos' — re-importing ONLY the skipped
lines so first-pass rows can't double-import (UX-20). Two real fixes
found en route: the mobile list ignored undo-pending deletes and used
en-US dates; the desktop date column also lost its en-US stray. Note:
UX-11 (no mobile layout) was a false positive — a card layout already
existed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/components/PasteImportModal.tsx

@@ -1,6 +1,10 @@
 import { useState } from 'react';
 import { ClipboardPaste, CheckCircle, AlertTriangle } from 'lucide-react';
+import { toast } from 'sonner';
+
 import api, { type ImportResult } from '@/lib/api';
+import { formatAmount } from '@/lib/format';
+import { formatShortDate } from '@/lib/dates';
 import { Button } from '@/components/ui/button';
 import { Label } from '@/components/ui/label';
 import { Textarea } from '@/components/ui/textarea';
@@ -39,8 +43,40 @@ export default function PasteImportModal({ onClose, onImported }: Props) {
       const { data } = await api.post<ImportResult>('/import/paste', { text, bank, source });
       setResult(data);
       if (data.imported > 0) onImported();
-    } catch (err) {
-      console.error(err);
+    } catch {
+      toast.error('No se pudo importar - revisa el formato');
+    } finally {
+      setImporting(false);
+    }
+  };
+
+  // Re-import ONLY the skipped lines with the dedup check disabled, so rows
+  // that imported on the first pass are never duplicated.
+  const handleImportDuplicates = async () => {
+    if (!result || result.skipped.length === 0) return;
+    const lines = text.trim().split('\n');
+    const dupText = result.skipped
+      .map((s) => lines[s.line - 1])
+      .filter(Boolean)
+      .join('\n');
+    setImporting(true);
+    try {
+      const { data } = await api.post<ImportResult>('/import/paste', {
+        text: dupText,
+        bank,
+        source,
+        allow_duplicates: true,
+      });
+      toast.success(`${data.imported} duplicado(s) importados`);
+      setResult({
+        ...result,
+        imported: result.imported + data.imported,
+        skipped: [],
+        duplicates: 0,
+      });
+      onImported();
+    } catch {
+      toast.error('No se pudieron importar los duplicados');
     } finally {
       setImporting(false);
     }
@@ -134,6 +170,39 @@ export default function PasteImportModal({ onClose, onImported }: Props) {
               </Alert>
             )}
 
+            {result.skipped.length > 0 && (
+              <div className="rounded-lg border border-amber-500/40 bg-amber-500/5 p-3 space-y-2">
+                <p className="text-sm font-medium">
+                  {result.skipped.length} duplicado(s) omitido(s)
+                </p>
+                <ul className="text-xs max-h-40 overflow-y-auto space-y-1.5">
+                  {result.skipped.map((s) => (
+                    <li key={`${s.line}-${s.existing_id}`} className="space-y-0.5">
+                      <span className="font-mono">
+                        {s.merchant} · {formatShortDate(s.date)} ·{' '}
+                        {formatAmount(s.amount, s.currency)}
+                      </span>
+                      <span className="block text-muted-foreground">
+                        coincide con #{s.existing_id}: {s.existing_merchant} del{' '}
+                        {formatShortDate(s.existing_date)} ({s.existing_source})
+                      </span>
+                    </li>
+                  ))}
+                </ul>
+                <Button
+                  variant="outline"
+                  size="sm"
+                  className="w-full"
+                  onClick={handleImportDuplicates}
+                  disabled={importing}
+                >
+                  {importing
+                    ? 'Importando...'
+                    : 'Importar duplicados de todos modos'}
+                </Button>
+              </div>
+            )}
+
             <Button onClick={onClose} className="w-full">
               Done
             </Button>