feat(imports): import history and delete by import

Track imports in DB, show history in Data section, allow deleting
transactions of a specific import instead of clearing all.

frontend/src/components/DeleteImportModal.tsx

@@ -0,0 +1,70 @@
+import { useState } from 'react';
+import { deleteImport } from '../api/import';
+import type { Import } from '@family-budget/shared';
+
+interface Props {
+  imp: Import;
+  onClose: () => void;
+  onDone: () => void;
+}
+
+export function DeleteImportModal({ imp, onClose, onDone }: Props) {
+  const [loading, setLoading] = useState(false);
+  const [error, setError] = useState('');
+
+  const accountLabel =
+    imp.accountAlias || imp.accountNumberMasked || `ID ${imp.accountId}`;
+
+  const handleConfirm = async () => {
+    setLoading(true);
+    setError('');
+    try {
+      await deleteImport(imp.id);
+      onDone();
+    } catch (e) {
+      setError(
+        e instanceof Error ? e.message : 'Ошибка при удалении импорта',
+      );
+    } finally {
+      setLoading(false);
+    }
+  };
+
+  return (
+    <div className="modal-overlay" onClick={onClose}>
+      <div className="modal" onClick={(e) => e.stopPropagation()}>
+        <div className="modal-header">
+          <h2>Удалить импорт</h2>
+          <button className="btn-close" onClick={onClose}>
+            &times;
+          </button>
+        </div>
+
+        <div className="modal-body">
+          <p className="clear-history-warn">
+            Будут удалены все операции этого импорта ({imp.importedCount}{' '}
+            шт.): {imp.bank} / {accountLabel}
+          </p>
+
+          {error && <div className="alert alert-error">{error}</div>}
+
+          <p>Действие необратимо.</p>
+        </div>
+
+        <div className="modal-footer">
+          <button
+            type="button"
+            className="btn btn-danger"
+            onClick={handleConfirm}
+            disabled={loading}
+          >
+            {loading ? 'Удаление…' : 'Удалить'}
+          </button>
+          <button type="button" className="btn btn-secondary" onClick={onClose}>
+            Отмена
+          </button>
+        </div>
+      </div>
+    </div>
+  );
+}