style(ocr): add Image type hints to extract_page_blocks and extract_region_text

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

ocr-service/engines/kraken.py

@@ -1,9 +1,15 @@
 """Kraken OCR engine wrapper — historical HTR model support for Kurrent/Suetterlin."""
 
+from __future__ import annotations
+
 import collections
 import logging
 import os
 import threading
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from PIL.Image import Image
 
 logger = logging.getLogger(__name__)
 
@@ -94,7 +100,7 @@ def is_available() -> bool:
     return _model is not None
 
 
-def extract_page_blocks(image, page_idx: int, language: str = "de",
+def extract_page_blocks(image: Image, page_idx: int, language: str = "de",
                          sender_model_path: str | None = None) -> list[dict]:
     """Run Kraken segmentation + recognition on a single PIL image.
 
@@ -148,7 +154,7 @@ def extract_page_blocks(image, page_idx: int, language: str = "de",
     return blocks
 
 
-def extract_region_text(image, x: float, y: float, w: float, h: float,
+def extract_region_text(image: Image, x: float, y: float, w: float, h: float,
                          sender_model_path: str | None = None) -> str:
     """Crop image to a normalized region and run Kraken recognition on the crop.