* Materialize the SQL view into a regular table populated by a nightly
  cron, in case real-time aggregation becomes too slow on very large
  POS datasets.
* Refine the ``is_member_at_date`` calculation by consuming
  ``subscription.register`` to subtract sell-back and transfer
  operations from the share balance. The current implementation simply
  checks for the existence of a ``share.line`` dated on or before the
  order date, which over-reports memberships when shares are returned.
* Add multi-company test coverage once a clean multi-company test
  fixture is available.
* Add Galician, Catalan, French, Dutch and Croatian translations
  (currently shipped with Spanish only).
