Restructure: Move ocr_pipeline + labeling + crop into ocr/ package

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

klausur-service/backend/ocr_pipeline_overlays.py

@@ -1,34 +1,4 @@
-"""
-Overlay image rendering for OCR pipeline — barrel re-export.
-
-All implementation split into:
-  ocr_pipeline_overlay_structure — structure overlay (boxes, zones, colors, graphics)
-  ocr_pipeline_overlay_grid     — columns, rows, words overlays
-
-Lizenz: Apache 2.0
-DATENSCHUTZ: Alle Verarbeitung erfolgt lokal.
-"""
-
-from fastapi import HTTPException
-from fastapi.responses import Response
-
-from ocr_pipeline_overlay_structure import _get_structure_overlay  # noqa: F401
-from ocr_pipeline_overlay_grid import (  # noqa: F401
-    _get_columns_overlay,
-    _get_rows_overlay,
-    _get_words_overlay,
-)
-
-
-async def render_overlay(overlay_type: str, session_id: str) -> Response:
-    """Dispatch to the appropriate overlay renderer."""
-    if overlay_type == "structure":
-        return await _get_structure_overlay(session_id)
-    elif overlay_type == "columns":
-        return await _get_columns_overlay(session_id)
-    elif overlay_type == "rows":
-        return await _get_rows_overlay(session_id)
-    elif overlay_type == "words":
-        return await _get_words_overlay(session_id)
-    else:
-        raise HTTPException(status_code=400, detail=f"Unknown overlay type: {overlay_type}")
+# Backward-compat shim -- module moved to ocr/pipeline/overlays.py
+import importlib as _importlib
+import sys as _sys
+_sys.modules[__name__] = _importlib.import_module("ocr.pipeline.overlays")