fix(models): isolate versioned migration sessions

backend/internal/models/migrations_test.go

@@ -35,7 +35,10 @@ func TestAutoMigrateUpgradesLegacyProjectsAndTagsWithoutLosingAssociations(t *te
 		require.NoError(t, database.Exec(statement).Error)
 	}
 
-	require.NoError(t, AutoMigrate(database))
+	// PostgreSQL migrations run through database.Connection, whose callback DB can
+	// carry an initialized Gorm statement. Exercise that mode so model state from
+	// the migration-version lookup cannot leak into the data-repair transaction.
+	require.NoError(t, AutoMigrate(database.Session(&gorm.Session{Initialized: true})))
 
 	var projects []SenlinAgentProject
 	require.NoError(t, database.Order("id asc").Find(&projects).Error)