Consider moving 'name' field to 'entities' table.

'name' pops up in most concrete Entity tables. Common enough to add to 'entities', which would also allow us to look at Entities directly with some meaning. Should be thought of as "name or label".

Consider implementing along with #19.

Review the existing concrete Entity tables and the central entities table, then compare the related proposal in issue #19. Determine how a shared name-or-label field would affect the schema and existing consumers; done means the design and required migration changes are agreed and consistently applied.

Written by the indexing model from the issue text.