Delete Memories Bulk

Erase a user's personal memories (GDPR/CCPA erasure) from every store.

The same erasure as the deletion API's user_scope target, and audited the same way (a deletion request + receipt, purged after the retention window): every node in the user's personal scope (and their unstamped legacy nodes), the vectors stamped with it in every namespace, their personal active-tier fragments, turn index rows and edit history. This route used to tombstone engine nodes only — the active copies kept answering recall and inferences kept answering NLQ — and answered 500 on the first node it could see but not delete. deleted_count is engine nodes tombstoned.