Return the externally accessible kits for the calling API key.
kits and total.200 with an empty kits array means the key authenticated successfully but has no externally visible kits.exposed, which suggests an additional access grant or backend entitlement step beyond simply toggling exposure.GET /api/v1/external/kits returns 200HEAD /api/v1/external/kits returns 404OPTIONS /api/v1/external/kits returns 404