Restructure: Move 47 cv_* files into ocr/ package

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

klausur-service/backend/ocr/cell_grid/streaming.py

@@ -13,17 +13,17 @@ from typing import Any, Dict, Generator, List, Optional, Tuple
 
 import numpy as np
 
-from cv_vocab_types import PageRegion, RowGeometry
-from cv_ocr_engines import (
+from ..types import PageRegion, RowGeometry
+from ..engines.engines import (
     RAPIDOCR_AVAILABLE,
     _assign_row_words_to_columns,
 )
-from cv_cell_grid_helpers import (
+from .helpers import (
     _heal_row_gaps,
     _is_artifact_row,
 )
-from cv_cell_grid_build import _ocr_cell_crop
-from cv_cell_grid_legacy import _ocr_single_cell
+from .build import _ocr_cell_crop
+from .legacy import _ocr_single_cell
 
 logger = logging.getLogger(__name__)