feat: add Woerterbuch category + column add/delete in grid editor

- New document category "Woerterbuch" (frontend type + backend validation)
- Column delete: hover column header → red "x" button (with confirmation)
- Column add: hover column header → "+" button inserts after that column
- Both operations support undo/redo, update cell IDs and summary
- Available in both GridEditor and StepGridReview (Kombi last step)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-lehrer/components/ocr-pipeline/StepGridReview.tsx

@@ -41,6 +41,8 @@ export function StepGridReview({ sessionId, onNext }: StepGridReviewProps) {
     canUndo,
     canRedo,
     getAdjacentCell,
+    deleteColumn,
+    addColumn,
   } = useGridEditor(sessionId)
 
   const [showImage, setShowImage] = useState(true)
@@ -373,6 +375,8 @@ export function StepGridReview({ sessionId, onNext }: StepGridReviewProps) {
                           onToggleColumnBold={toggleColumnBold}
                           onToggleRowHeader={toggleRowHeader}
                           onNavigate={handleNavigate}
+                          onDeleteColumn={deleteColumn}
+                          onAddColumn={addColumn}
                         />
                       </div>
                     ))}