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/legacy.py

@@ -12,8 +12,8 @@ from typing import Any, Dict, 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,
     _clean_cell_text,
@@ -22,7 +22,7 @@ from cv_ocr_engines import (
     ocr_region_rapid,
     ocr_region_trocr,
 )
-from cv_cell_grid_helpers import (
+from .helpers import (
     _MIN_WORD_CONF,
     _compute_cell_padding,
     _ensure_minimum_crop_size,