fix(test): drop unused Post binding in test_importer_provenance_race (ruff F841)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_importer_provenance_race.py

@@ -29,7 +29,6 @@ from backend.app.models import (
     ImageProvenance,
     ImageRecord,
     ImportSettings,
-    Post,
     Source,
 )
 from backend.app.services.importer import Importer
@@ -140,7 +139,6 @@ def test_apply_sidecar_recovers_from_integrity_error(
     r = importer.import_one(m)
     assert r.status == "imported"
     rec = importer.session.get(ImageRecord, r.image_id)
-    post = importer.session.execute(select(Post)).scalar_one()
     src = importer.session.execute(select(Source)).scalar_one()
     assert rec is not None
     assert src is not None