Past photos a rule would tag (they match and don't have its result yet), for the "Review past photos" step. Read-only; the rule may be unsaved (a draft or an edit).

Body: { projectId, rule: { conditions, thenCategory, thenValue?, thenPersonId? }, groupId? } groupId: the group the rule is/will be in — a group with a day only shows that day's photos. Returns { images: [{ id, title, dateTaken, thumbnailUrl, url, tags: {category: [tag]} }], total, truncated }. Photographers get only their own photos, as in /getImages.