When exclude regions are saved or deleted, the cached grid result is
cleared so the grid rebuilds with updated exclusions on the next step.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Users can now draw rectangles on the document image in the Structure
Detection step to mark areas (e.g. header graphics, alphabet strips)
that should be excluded from OCR results during grid building.
- Backend: PUT/DELETE endpoints for exclude regions stored in structure_result
- Backend: _build_grid_core() filters all words inside user-defined exclude regions
- Frontend: Interactive rectangle drawing with visual overlay and delete buttons
- Preserve exclude regions when re-running structure detection
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>