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

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

klausur-service/backend/page_crop.py

@@ -1,33 +1,4 @@
-"""
-Page Crop — Barrel Re-export
-
-Content-based crop for scanned pages and book scans.
-
-Split into:
-- page_crop_edges.py  — Edge detection (spine shadow, gutter, projection)
-- page_crop_core.py   — Main crop algorithm and format detection
-
-All public names are re-exported here for backward compatibility.
-License: Apache 2.0
-"""
-
-# Core: main crop functions and format detection
-from page_crop_core import (  # noqa: F401
-    PAPER_FORMATS,
-    detect_page_splits,
-    detect_and_crop_page,
-    _detect_format,
-)
-
-# Edge detection helpers
-from page_crop_edges import (  # noqa: F401
-    _INK_THRESHOLD,
-    _MIN_RUN_FRAC,
-    _detect_spine_shadow,
-    _detect_gutter_continuity,
-    _detect_left_edge_shadow,
-    _detect_right_edge_shadow,
-    _detect_top_bottom_edges,
-    _detect_edge_projection,
-    _filter_narrow_runs,
-)
+# Backward-compat shim -- module moved to ocr/pipeline/page_crop.py
+import importlib as _importlib
+import sys as _sys
+_sys.modules[__name__] = _importlib.import_module("ocr.pipeline.page_crop")