To enable moderators to assess the usage of reactions, which were recently introduced in #553, it is probably a good idea to show the number of times the reaction has been used in the moderator tools (/posts/reactions).

Possible implementations (just ideas):

• as a new column in the main table ("usage")
• as a new table (with columns, such as "usage overall", "usage last week" and "usage last month"?)

Complexity consideration:

adding some frontend markup (column or new table), some level of DB-access (likely all in frontend code), some query complexity -> should be a good easy issue to get along with the QPixel structure