Assert account directory cursor fidelity in migration

Why: The U3 migration must replace the target schema seed with the source directory revision and cursor key.

Evidence: Isolated PostgreSQL TestMigrateEndToEndAndIdempotent passed with field-by-field source and target comparison.

Impact: Migration regressions that lose directory cursor identity now fail the existing end-to-end test.

Refs: IAM U3 Stage 7; docs/proposals/2026-10-14-iam-u3-account-contract-and-plan.md §10

cmd/storage-migrate/integration_test.go

@@ -45,6 +45,18 @@ func TestMigrateEndToEndAndIdempotent(t *testing.T) {
 	target, cleanup := pgSchemaDSN(t)
 	defer cleanup()
 	fixture := buildFixture(t)
+	src, err := sql.Open("sqlite", fixture)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer src.Close()
+	var sourcePublic, sourceStaff, sourcePrivate, sourceSecret string
+	var sourceKeyVersion int64
+	if err := src.QueryRow(`SELECT public_revision,staff_no_revision,private_revision,cursor_key_version,cursor_secret FROM account_directory_revision WHERE id=1`).Scan(
+		&sourcePublic, &sourceStaff, &sourcePrivate, &sourceKeyVersion, &sourceSecret,
+	); err != nil {
+		t.Fatal(err)
+	}
 
 	if err := cmdMigrate([]string{"--source", fixture, "--target", target, "--migration-id", "mig-e2e"}); err != nil {
 		t.Fatalf("首次迁移：%v", err)
@@ -61,6 +73,16 @@ func TestMigrateEndToEndAndIdempotent(t *testing.T) {
 	}
 	defer st.Close()
 	db := st.DB()
+	var targetPublic, targetStaff, targetPrivate, targetSecret string
+	var targetKeyVersion int64
+	if err := db.QueryRow(`SELECT public_revision,staff_no_revision,private_revision,cursor_key_version,cursor_secret FROM account_directory_revision WHERE id=1`).Scan(
+		&targetPublic, &targetStaff, &targetPrivate, &targetKeyVersion, &targetSecret,
+	); err != nil {
+		t.Fatal(err)
+	}
+	if targetPublic != sourcePublic || targetStaff != sourceStaff || targetPrivate != sourcePrivate || targetKeyVersion != sourceKeyVersion || targetSecret != sourceSecret {
+		t.Fatal("迁移后的目录版本或游标密钥与源库不一致")
+	}
 	var pinned, archived bool
 	if err := db.QueryRow(`SELECT pinned, archived FROM conversations WHERE id='c1'`).Scan(&pinned, &archived); err != nil || !pinned || archived {
 		t.Fatalf("布尔映射：pinned=%v archived=%v err=%v", pinned, archived, err)