Tool registrar receiving key tools.
Repository-owned B2 native client.
Auth manager used for account-scoped key requests.
Server configuration for secret-sink and destructive policy.
Registration controls; registerDurableSecretSchemas forces
the full b2_create_key schema even without an active sink (discovery mode,
where execution is guarded separately) so tools/list advertises real inputs.
Register B2 application-key management tools.