Replace box picker with free-text location in audit scan

"Where found" during inventory audit is now a plain text field
(e.g. "каб. 305") stored on the object instead of assigning it to a
box, since audit walks often use room/office labels that don't map
to the box/shelf hierarchy used elsewhere. Box assignment via the
regular object form is unaffected.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/app/routers/objects.py

@@ -59,7 +59,7 @@ async def scan_object(db: DbSession, _: CurrentUser, object_id: uuid.UUID, data:
     obj = await objects_service.get_object(db, object_id)
     if obj is None:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Object not found")
-    obj = await objects_service.mark_object_found(db, obj, data.box_id)
+    obj = await objects_service.mark_object_found(db, obj, data.location)
     return objects_service.build_object_read(obj)