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/grid/editor/api_unified.py

@@ -6,7 +6,7 @@ import logging
 
 from fastapi import APIRouter, HTTPException
 
-from ocr_pipeline_session_store import (
+from ocr.pipeline.session_store import (
     get_session_db,
     update_session_db,
 )
@@ -32,7 +32,7 @@ async def build_unified_grid_endpoint(session_id: str):
     if not grid_data:
         raise HTTPException(status_code=400, detail="No grid data. Run build-grid first.")
 
-    from unified_grid import build_unified_grid
+    from grid.unified import build_unified_grid
 
     result = build_unified_grid(
         zones=grid_data.get("zones", []),