feat: add campaign copying scheduling and residual handling

tests/test_search_source.py

@@ -20,6 +20,7 @@ from govoplan_core.core.search import (
     SearchBackfillRequest,
     SearchResourceReference,
 )
+from govoplan_core.core.change_sequence import ChangeSequenceEntry
 from govoplan_core.db.base import Base
 
 
@@ -34,6 +35,7 @@ class CampaignSearchSourceTests(unittest.TestCase):
                 Group.__table__,
                 Campaign.__table__,
                 CampaignShare.__table__,
+                ChangeSequenceEntry.__table__,
             ),
         )
         self.session = Session(self.engine)