0c9dffed78
Caught live 2026-08-01 importing a bundle into the empty env2 cluster: a create-missing Site has Id == 0 until SaveChanges on a relational provider, and ApplyDataConnectionsAsync stamps DataConnection.SiteId as a raw scalar (no navigation, no EF fix-up), so the insert violated FK_DataConnections_Sites_SiteId. Every importer integration test runs on the EF in-memory provider, which assigns ids eagerly on AddAsync — the exact masking the in-code comment predicted. Fix: one SaveChangesAsync between the site pass and the connection pass, riding the same outer transaction (all-or-nothing preserved; the failed live import rolled back cleanly). Regression test runs the create-missing path on SQLite (CreateMissingSiteRelationalTests) — red without the fix, green with it.