Add type hints and fix mypy

Signed-off-by: Christoph Auer <cau@zurich.ibm.com>

docling/models/base_ocr_model.py

@@ -7,6 +7,7 @@ from typing import List, Optional, Type
 
 import numpy as np
 from docling_core.types.doc import BoundingBox, CoordOrigin
+from docling_core.types.doc.page import TextCell
 from PIL import Image, ImageDraw
 from rtree import index
 from scipy.ndimage import binary_dilation, find_objects, label
@@ -107,7 +108,9 @@ class BaseOcrModel(BasePageModel, BaseModelWithOptions):
             return []
 
     # Filters OCR cells by dropping any OCR cell that intersects with an existing programmatic cell.
-    def _filter_ocr_cells(self, ocr_cells, programmatic_cells):
+    def _filter_ocr_cells(
+        self, ocr_cells: List[TextCell], programmatic_cells: List[TextCell]
+    ) -> List[TextCell]:
         # Create R-tree index for programmatic cells
         p = index.Property()
         p.dimension = 2
@@ -130,7 +133,7 @@ class BaseOcrModel(BasePageModel, BaseModelWithOptions):
         ]
         return filtered_ocr_cells
 
-    def post_process_cells(self, ocr_cells, page):
+    def post_process_cells(self, ocr_cells: List[TextCell], page: Page) -> None:
         r"""
         Post-process the OCR cells and update the page object.
         Updates parsed_page.textline_cells directly since page.cells is now read-only.
@@ -147,7 +150,9 @@ class BaseOcrModel(BasePageModel, BaseModelWithOptions):
         page.parsed_page.textline_cells = final_cells
         page.parsed_page.has_lines = len(final_cells) > 0
 
-    def _combine_cells(self, existing_cells, ocr_cells):
+    def _combine_cells(
+        self, existing_cells: List[TextCell], ocr_cells: List[TextCell]
+    ) -> List[TextCell]:
         """Combine existing and OCR cells with filtering and re-indexing."""
         if self.options.force_full_page_ocr:
             combined = ocr_cells