The /v1/default/banks/{bank_id}/stats endpoint was missing the
request_context parameter and tenant authentication call, causing
it to query the public schema instead of the tenant's schema.
This resulted in stats always returning zeros for multi-tenant
deployments since the data lives in tenant-specific schemas.
Added request_context dependency and _authenticate_tenant() call
to properly set the tenant schema before querying stats.
d6ff191198