List the data points a question can be built from, by template

The same catalogue as /data-points, grouped into one entry per profile template — the shape a question library sidebar renders. category is the template id that groups the entry, name its display label. Each data point additionally carries id, an alias of retracedId. A template whose data points are all excluded from questionnaires still appears, with an empty list. The catalogue is global rather than company-scoped, and unpaginated.