[upstream #17050] Drain Assistants runs before erasing the account (#17050) #352

Codex finding on LibreChat-AI#17050: LibreChat-AI#17050 (comment)

Assistants v1 and v2 chat runs do not create a GenerationJobManager job, so stopUserGenerations cannot see or cancel them. A run that passed requireJwtAuth just before an account deletion fence can reach saveAssistantMessage after eraseUserData and recreate messages and conversation state for the deleted user. Pre-existing on the base for self-service deletion. Fix: register Assistants runs with the account cleanup barrier, or add a post-auth deletion check and drain before their persistence steps.