LiteLLM requires unique key aliases, so re-creating a key with an existing
(email, name) pair 400s ('alias already exists') — breaking key rotation
from the dashboard. The stored LiteLLM hash lets us retire the old key
first; the ON CONFLICT upsert then tracks the new key.
Surfaced by the LibreChat sandbox work: the portal chat-key rotation for
an SSO member failed with exactly this 400.