feat: govern shared campaign artifact storage

src/govoplan_campaign/backend/route_support.py

@@ -645,17 +645,9 @@ def _clear_current_version_mail_profile_for_owner_transfer(
 
 
 def _write_current_version_snapshot_if_available(version: CampaignVersion) -> None:
-    try:
-        from govoplan_campaign.backend.persistence.campaigns import (
-            _write_campaign_snapshot,
-        )
-
-        _write_campaign_snapshot(version)
-    except Exception:
-        # The database state is authoritative for the WebUI. Snapshot writing is
-        # best-effort here because ownership changes should not fail due to an
-        # unavailable local runtime directory.
-        return
+    # Kept as a compatibility no-op for callers outside this package. Campaign
+    # JSON is database-authoritative and no longer mirrored onto an API node.
+    del version
 
 
 def bounded_query_rows(query, *, limit: int, label: str):