[BUG] MetaDataServiceImpl.deleteByIdsAndNamespaceId / enabledByIdsAndNamespaceId missing @Transactional

- severity: Medium
- files: `shenyu-admin/src/main/java/org/apache/shenyu/admin/service/impl/MetaDataServiceImpl.java:110-136`
- description: `deleteByIdsAndNamespaceId` (110) and `enabledByIdsAndNamespaceId` (124) are not `@Transactional`, unlike `createOrUpdate`/`importData`. `deleteByIdsAndNamespaceId` does select → delete → `publisher.onDeleted`; without a transaction the delete commits before the event. `enabledByIdsAndNamespaceId` mutates the loaded VOs (`setEnabled`) and publishes them via `publisher.onEnabled` — but if the DB update returns 0 rows, it still proceeds to publish the mutated (stale) VOs as if enabled.
- impact: Inconsistent state between DB and sync consumers on enable; events may describe a state that was not persisted.
- suggested_fix: Annotate both methods `@Transactional(rollbackFor = Exception.class)`; gate `publisher.onEnabled` on the actual update count.
- confidence: Medium
- related_existing: none. N2 is the cross-namespace update bug in the same method; this is the transaction/event gap.

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_Identified during the 2026-08-02 deep re-scan; full list in [`docs/scan2-2026-08-02/06-medium-tiers.md`](docs/scan2-2026-08-02/06-medium-tiers.md)._

Start in shenyu-admin/src/main/java/org/apache/shenyu/admin/service/impl/MetaDataServiceImpl.java:110-136 and compare these methods with createOrUpdate and importData. Confirm that deleteByIdsAndNamespaceId and enabledByIdsAndNamespaceId use the required transaction behavior, and that onEnabled is not published when the database update affects zero rows.

Written by the indexing model from the issue text.