Fix: Update all old-style imports inside packages to new paths

65 files in klausur-service packages + 3 in backend-lehrer packages
had stale imports referencing deleted shim modules.

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

klausur-service/backend/ocr/pipeline/words.py

@@ -23,7 +23,7 @@ import numpy as np
 from fastapi import APIRouter, HTTPException
 from pydantic import BaseModel
 
-from cv_words_first import build_grid_from_words
+from ocr.words_first import build_grid_from_words
 from .session_store import (
     get_session_db,
     get_session_image,
@@ -72,7 +72,7 @@ async def paddle_direct(session_id: str):
 
     img_h, img_w = img_bgr.shape[:2]
 
-    from cv_ocr_engines import ocr_region_paddle
+    from ocr.engines.engines import ocr_region_paddle
 
     t0 = time.time()
     word_dicts = await ocr_region_paddle(img_bgr, region=None)