Bind an invoice series to the caller mobile device so only that device can issue invoices against it.
device_id stored on its user_session). Once locked:
POST /invoices with a locked series_id receive a series_locked_to_device error.POST /invoice-series/{id}/reserve-numbers to pre-allocate numbers for offline use./auth/login). The JWT’s backing user_session must have a non-empty device_id — re-authenticate from the app if device_id_missing is returned.true after a successful lock.